soc/intel/{alderlake,apollolake}: Remove unused <string.h>

Found using:
diff <(git grep -l '#include <string.h>' -- src/) <(git grep -l 'STRINGIFY\|memcpy\|memmove\|memset\|memcmp\|memchr\|strdup\|strconcat\|strnlen\|strlen\|strchr\|strncpy\|strcpy\|strcmp\|strncmp\|strspn\|strcspn\|strstr\|strtok_r\|strtok\|atol\|strrchr\|skip_atoi\|snprintf' -- src/)|grep '<'

Change-Id: Iacf390e98eaa3e855e1df78acdee3f738945a1d2
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50693
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/soc/intel/alderlake/bootblock/report_platform.c

@@ -17,7 +17,6 @@
 #include <intelblocks/mp_init.h>
 #include <soc/bootblock.h>
 #include <soc/pci_devs.h>
-#include <string.h>
 
 static struct {
 	u32 cpuid;

src/soc/intel/apollolake/acpi.c

@@ -19,7 +19,6 @@
 #include <soc/nvs.h>
 #include <soc/pci_devs.h>
 #include <soc/systemagent.h>
-#include <string.h>
 
 #include "chip.h"