pit: kirby: snow: Fix snow, fix up pit and kirby write protect.

A recent change to support early firmware selection on ARM broke snow and was
incompletely implemented on pit and kirby. This change fixes snow by applying
the remaining part of the change that had been applied to the other two
boards, and also hooks up real values in the get_write_protect_state function.

BUG=None
TEST=Built and booted on snow and pit, built for kirby.
BRANCH=None

Change-Id: Ifef7ad1bf399f79353daec3dd46973f2b2022e37
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/169120
Reviewed-by: David Hendrix <dhendrix@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>

src/mainboard/google/kirby/chromeos.c

@@ -101,5 +101,5 @@ int get_recovery_mode_switch(void)
 
 int get_write_protect_state(void)
 {
-	return 0; // FIXME what GPIO? // WP hard coded to disabled
+	return !gpio_get_value(GPIO_X30);
 }

src/mainboard/google/pit/chromeos.c

@@ -101,5 +101,5 @@ int get_recovery_mode_switch(void)
 
 int get_write_protect_state(void)
 {
-	return 0; // FIXME what GPIO? // WP hard coded to disabled
+	return !gpio_get_value(GPIO_X30);
 }

src/mainboard/google/snow/chromeos.c

@@ -99,7 +99,7 @@ int get_recovery_mode_switch(void)
 		  EC_HOST_EVENT_MASK(EC_HOST_EVENT_KEYBOARD_RECOVERY));
 }
 
-int get_recovery_mode_from_vbnv(void)
+int get_write_protect_state(void)
 {
-	return 0;
+	return !gpio_get_value(GPIO_D16);
 }