src: Remove unused 'include <stdint.h>

Found using:
diff <(git grep -l '#include <stdint.h>' -- src/) <(git grep -l 'int8_t\|int16_t\|int32_t\|int64_t\|intptr_t\|intmax_t\|s8\|u8\|s16\|u16\|s32\|u32\|s64\|u64\|INT8_MIN\|INT8_MAX\|INT16_MIN\|INT16_MAX\|INT32_MIN\|INT32_MAX\|INT64_MIN\|INT64_MAX\|INTMAX_MIN\|INTMAX_MAX' -- src/) |grep -v vendorcode |grep '<'

Change-Id: I5e14bf4887c7d2644a64f4d58c6d8763eb74d2ed
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41827
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/commonlib/include/commonlib/region.h

@@ -4,7 +4,6 @@
 #define _REGION_H_
 
 #include <sys/types.h>
-#include <stdint.h>
 #include <stddef.h>
 #include <stdbool.h>
 #include <commonlib/mem_pool.h>