soc/intel/xeon_sp: accomodate xeon_sp FSPX_CONFIG definitions

Intel FSPs of XEON server platforms define FSPX_CONFIG
instead of FSP_X_CONFIG, which is expected by coreboot.

Re-define in the common code.

Update coreboot code to use FSP_X_CONFIG consistently.

Tested=On OCP Delta Lake, boot up OS successfully.

Signed-off-by: Jonathan Zhang <jonzhang@fb.com>
Signed-off-by: Johnny Lin <johnny_lin@wiwynn.com>

Change-Id: Ifa0e1efa1618fbec84f1e1f23d9e49f3b1057b32
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69090
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/vendorcode/intel/fsp/fsp2_0/skylake_sp/FspmUpd.h

@@ -553,7 +553,7 @@ typedef struct {
 /** Offset 0x01E0
 **/
 	UINT8                     ReservedMemoryInitUpd[16];
-} FSP_M_CONFIG;
+} FSPM_CONFIG;
 
 /** Fsp M UPD Configuration
 **/