pinctrl: sh-pfc: r8a7795: Use lookup function for bias data

There is a bug in the r8a7795 bias code where a WARN() is trigged
anytime a pin from PUEN0/PUD0 is accessed.

 # cat /sys/kernel/debug/pinctrl/e6060000.pfc/pinconf-pins

 WARNING: CPU: 2 PID: 2391 at drivers/pinctrl/sh-pfc/pfc-r8a7795.c:5364 r8a7795_pinmux_get_bias+0xbc/0xc8
 [..]
 Call trace:
 [<ffff0000083c442c>] r8a7795_pinmux_get_bias+0xbc/0xc8
 [<ffff0000083c37f4>] sh_pfc_pinconf_get+0x194/0x270
 [<ffff0000083b0768>] pin_config_get_for_pin+0x20/0x30
 [<ffff0000083b11e8>] pinconf_generic_dump_one+0x168/0x188
 [<ffff0000083b144c>] pinconf_generic_dump_pins+0x5c/0x98
 [<ffff0000083b0628>] pinconf_pins_show+0xc8/0x128
 [<ffff0000081fe3bc>] seq_read+0x16c/0x420
 [<ffff00000831a110>] full_proxy_read+0x58/0x88
 [<ffff0000081d7ad4>] __vfs_read+0x1c/0xf8
 [<ffff0000081d8874>] vfs_read+0x84/0x148
 [<ffff0000081d9d64>] SyS_read+0x44/0xa0
 [<ffff000008082f4c>] __sys_trace_return+0x0/0x4

This is due to the WARN() check if the reg field of the pullups struct
is zero, and this should be 0 for pins controlled by the PUEN0/PUD0
registers since PU0 is defined as 0. Change the data structure and use
the generic sh_pfc_pin_to_bias_info() function to get the register
offset and bit information.

Fixes: 56065524 ("pinctrl: sh-pfc: r8a7795: Add bias pinconf support")
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>