vc/intel/fsp/mtl: Organize FSP headers into x86_32 directory

This commit moves FSP V3471.91 header files for Meteor Lake
into a new x86_32 directory to better organize the files based
on the architecture. The Kconfig file has been modified accordingly
to reflect the new paths of the relocated headers.

BUG=b:329034258
TEST=Verified x86_32 and x86_64 builds on Meteor Lake board (Rex)

Change-Id: Id30186a8b1b5a9082f498e18a3378f5e9907b668
Signed-off-by: Appukuttan V K <appukuttan.vk@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82424
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Dinesh Gehlot <digehlot@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>

src/soc/intel/meteorlake/Kconfig

@@ -347,7 +347,7 @@ config CONSOLE_CBMEM_BUFFER_SIZE
 
 config FSP_HEADER_PATH
 	string "Location of FSP headers"
-	default "src/vendorcode/intel/fsp/fsp2_0/meteorlake/"
+	default "src/vendorcode/intel/fsp/fsp2_0/meteorlake/x86_32/"
 
 config FSP_FD_PATH
 	string