commonlib/fsp_relocate.c: Use C99 flexible arrays

Use C99 flexible arrays instead of older style of one-element or
zero-length arrays.
It allows the compiler to generate errors when the flexible array does
not occur at the end in the structure.

Change-Id: I52b5a83e7e484889bfef5a4e45a0279fadd58890
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76784
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/commonlib/fsp_relocate.c

@@ -55,7 +55,7 @@ struct fsp_patch_table {
 	uint8_t header_revision;
 	uint8_t reserved;
 	uint32_t patch_entry_num;
-	uint32_t patch_entries[0];
+	uint32_t patch_entries[];
 } __packed;
 
 #define FSPP_SIG 0x50505346