drivers: spi: stm32: Skip pinctrl suspend/resume for subghzspi

Subghzspi instances cannot have any pinctrl configs. This causes a
failure of the power management suspend and resume operations for the
subghzspi instance because no "default" pinctrl is found.

Fix that by skipping the pinctrl parts on subghzspi instances.

At the same time fix a copy and paste in the suspend error message.

Fixes: b567a7db

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>