The error handling path is broken as cawake_gpio was defined as
unsigned integer causing the following warnings on boards that don't
use SSI port and so don't have cawake_gpio defined. e.g. beagleboard C4.

[   30.094635] WARNING: CPU: 0 PID: 322 at drivers/gpio/gpiolib.c:86 gpio_to_desc+0xa4/0xb8()
[   30.103363] invalid GPIO -2
[   30.106292] Modules linked in: omap_ssi_port(+) cpufreq_dt cfbfillrect cfbimgblt leds_gpio cfbcopyarea thermal_sys led_class hwmon gpio_keys encoder_tfp410 connector_analog_tv connector_dvi omap_hdq snd phy_i
[   30.145477] CPU: 0 PID: 322 Comm: modprobe Not tainted 4.3.0-rc4-00030-gca978c0-dirty #335
[   30.154174] Hardware name: Generic OMAP3-GP (Flattened Device Tree)
[   30.160827] [<c0016ef4>] (unwind_backtrace) from [<c00131f4>] (show_stack+0x10/0x14)
[   30.168975] [<c00131f4>] (show_stack) from [<c033cf08>] (dump_stack+0x80/0x9c)
[   30.176635] [<c033cf08>] (dump_stack) from [<c003e920>] (warn_slowpath_common+0x7c/0xb8)
[   30.185180] [<c003e920>] (warn_slowpath_common) from [<c003e9f0>] (warn_slowpath_fmt+0x30/0x40)
[   30.194366] [<c003e9f0>] (warn_slowpath_fmt) from [<c0376314>] (gpio_to_desc+0xa4/0xb8)
[   30.202819] [<c0376314>] (gpio_to_desc) from [<c0376ac8>] (gpio_request_one+0x14/0x11c)
[   30.211273] [<c0376ac8>] (gpio_request_one) from [<c037370c>] (devm_gpio_request_one+0x3c/0x78)
[   30.220458] [<c037370c>] (devm_gpio_request_one) from [<bf184210>] (ssi_port_probe+0x118/0x504 [omap_ssi_port])
[   30.231170] [<bf184210>] (ssi_port_probe [omap_ssi_port]) from [<c03d4cfc>] (platform_drv_probe+0x48/0xa4)
[   30.241424] [<c03d4cfc>] (platform_drv_probe) from [<c03d3678>] (driver_probe_device+0x1dc/0x2a0)
[   30.250793] [<c03d3678>] (driver_probe_device) from [<c03d37d0>] (__driver_attach+0x94/0x98)
[   30.259643] [<c03d37d0>] (__driver_attach) from [<c03d1d60>] (bus_for_each_dev+0x54/0x88)
[   30.268249] [<c03d1d60>] (bus_for_each_dev) from [<c03d2d50>] (bus_add_driver+0xe8/0x1f8)
[   30.276916] [<c03d2d50>] (bus_add_driver) from [<c03d4118>] (driver_register+0x78/0xf4)
[   30.285369] [<c03d4118>] (driver_register) from [<c03d5380>] (__platform_driver_probe+0x34/0xd8)
[   30.294647] [<c03d5380>] (__platform_driver_probe) from [<c00097e4>] (do_one_initcall+0x80/0x1d8)
[   30.303985] [<c00097e4>] (do_one_initcall) from [<c011617c>] (do_init_module+0x5c/0x1cc)
[   30.312561] [<c011617c>] (do_init_module) from [<c00c7a68>] (load_module+0x18c8/0x1f0c)
[   30.320983] [<c00c7a68>] (load_module) from [<c00c8188>] (SyS_init_module+0xdc/0x150)
[   30.329223] [<c00c8188>] (SyS_init_module) from [<c000f7e0>] (ret_fast_syscall+0x0/0x1c)

Fixes: b209e047 ("HSI: Introduce OMAP SSI driver")
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>