pcmcia: fix return value of soc_pcmcia_regulator_set

pcmcia: fix return value of soc_pcmcia_regulator_set

The newly introduced soc_pcmcia_regulator_set() function sometimes
returns without setting its return code, as shown by this warning:

  drivers/pcmcia/soc_common.c: In function 'soc_pcmcia_regulator_set':
  drivers/pcmcia/soc_common.c:112:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This changes it to propagate the regulator_disable() result instead.

Fixes: ac61b6001a63 ("pcmcia: soc_common: add support for Vcc and Vpp regulators")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>