intelblocks/pmc: Assign initial values to pmc_gpe_init variables

pmc_gpe_init uses soc_get_gpi_gpe_configs to initialize dw0, dw1
and dw2. dw0, dw1 and dw2 are uninitialized before calling
soc_get_gpi_gpe_configs. This is error prone for some soc
implementations where soc_get_gpi_gpe_configs does nothing.

This patch is simple, just to assign zero values to dw0, dw1 and
dw0, to enhance the code robustness.

TEST=intel/archercity CRB

Signed-off-by: Gang Chen <gang.c.chen@intel.com>
Change-Id: I8a710a2ac1482eed8c11977d51b187d834122d26
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81210
Reviewed-by: Jérémy Compostella <jeremy.compostella@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/common/block/pmc/pmclib.c

@@ -581,7 +581,7 @@ void pmc_gpe_init(void)
 {
 	uint32_t gpio_cfg = 0;
 	uint32_t gpio_cfg_reg;
-	uint8_t dw0, dw1, dw2;
+	uint8_t dw0 = 0, dw1 = 0, dw2 = 0;
 
 	/* Read PMC base address from soc. This is implemented in soc */
 	uintptr_t pmc_bar = soc_read_pmc_base();