x86, intel-mid: Check get_gpio_by_name() error code on platform code

This patch does cleanup on all intel mid platform code that uses
gpio_get_by_name() function. From now on they should check for any error
code instead of only hardcoded -1.

There are no functional changes from this change.

Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
Link: http://lkml.kernel.org/r/1389913624-9149-3-git-send-email-david.a.cohen@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>