We are missing pm_runtime_disable() in 2430 glue layer. Further,
we only need to enable PM runtime and disable it on exit. With
musb_core.c doing PM, the glue layer as a parent will always be
active when musb_core.c is active.

This fixes host enumeration issues with some devices as reported
by Ladislav Michl <ladis@linux-mips.org>.

And holding an RPM reference while deregistering the child would
lead to a crash in omap2430_runtime_suspend() which dereferences
the now freed child's driver data on put as pointed out by
Johan Hovold <johan@kernel.org>:

Unable to handle kernel paging request at virtual address 6b6b6f17
...
[<c05453d4>] (omap2430_runtime_suspend) from [<c0481410>]
 (pm_generic_runtime_suspend+0x3c/0x48)
[<c0481410>] (pm_generic_runtime_suspend) from [<c0121028>]
 (_od_runtime_suspend+0x1c/0x30)
[<c0121028>] (_od_runtime_suspend) from [<c04833b0>] (__rpm_callback+0x3c/0x70)
[<c04833b0>] (__rpm_callback) from [<c0483414>] (rpm_callback+0x30/0x90)
[<c0483414>] (rpm_callback) from [<c0483984>] (rpm_suspend+0x118/0x6b4)
[<c0483984>] (rpm_suspend) from [<c04840f4>] (rpm_idle+0x104/0x440)
[<c04840f4>] (rpm_idle) from [<c04844ac>] (__pm_runtime_idle+0x7c/0xb0)
[<c04844ac>] (__pm_runtime_idle) from [<c0545458>] (omap2430_remove+0x38/0x58)
[<c0545458>] (omap2430_remove) from [<c047b2bc>] (platform_drv_remove+0x34/0x4c)

Note that if changes are needed to the autosuspend timeout, it should
be done in musb_core.c.
Reported-by: Ladislav Michl <ladis@linux-mips.org>
Fixes: 87326e85 ("usb: musb: Remove extra PM runtime calls from
2430 glue layer")
Tested-by: Ladislav Michl <ladis@linux-mips.org>
Reviewed-by: Johan Hovold <johan@kernel.org>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>