drivers/gpio: stm32h7: Don't use HSEM_CR_COREID_CURRENT as process id

HSEM_CR_COREID_CURRENT was used as process number parameter in
LL_HSEM_ReleaseLock function. While this is working, this
define should not be used in this context.
Also, process number parameter is actually proposed in case of HSEM
use in inter-process context but is not required for inter-core
resource lock. Replace HSEM_CR_COREID_CURRENT with 0.

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>