serial/amba-pl011: move custom pin control to driver

We had a boot regression in Ux500 in the merge window because
two orthogonal pin control schemes for the PL011 were merged
at the same time:

- One using the .init() and .exit() hooks into the platform
  for Ux500 putting the pins into default vs sleep state
  respectively as the port was started/stopped.
  commit a0980660
  "ARM: ux500: switch to using pinctrl for uart0"

- One hogging the default setting at PL011 probe()
  commit 258e0551
  "serial: amba-pl011: adopt pinctrl support"

To get a solution that works for both let's scrap the stuff
in the platform callbacks, instead have the driver itself
select default and sleep states when the port is
started/stopped. Hopefully this works for all clients.
Platform callbacks are bad for device tree migration anyway,
so this rids us of another problem in Ux500.

Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Reported-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>