mb/google/brya: Remove baseboard-specific FMD names

This patch renames the 16MB FMD file to remove the baseboard-specific
name 'Nissa'. This allows other supported baseboards to utilize the
16MB SPI flash. Additionally, the patch attempts to create a generic,
unified 32MB FMD file for both brya and nissa variants.

BUG=b:333314089
TEST=Build and boot Nivviks.

Change-Id: I9151a4bcbe9cc084cc19b1a3e91c0321fe4dcc37
Signed-off-by: Dinesh Gehlot <digehlot@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81676
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Eric Lai <ericllai@google.com>
Reviewed-by: Varshit Pandya <pandyavarshit@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/brya/chromeos-16MiB-debugfsp.fmd

@@ -0,0 +1,42 @@
+FLASH 16M {
+	SI_ALL 3712K {
+		SI_DESC 4K
+		SI_ME
+	}
+	SI_BIOS 12672K {
+		RW_SECTION_A 4212K {
+			VBLOCK_A 8K
+			FW_MAIN_A(CBFS)
+			RW_FWID_A 64
+		}
+		RW_MISC 152K {
+			UNIFIED_MRC_CACHE(PRESERVE) 128K {
+				RECOVERY_MRC_CACHE 64K
+				RW_MRC_CACHE 64K
+			}
+			RW_ELOG(PRESERVE) 4K
+			RW_SHARED 4K {
+				SHARED_DATA 4K
+			}
+			RW_VPD(PRESERVE) 8K
+			RW_NVRAM(PRESERVE) 8K
+		}
+		RW_SECTION_B 4212K {
+			VBLOCK_B 8K
+			FW_MAIN_B(CBFS)
+			RW_FWID_B 64
+		}
+		# Make WP_RO region align with SPI vendor
+		# memory protected range specification.
+		WP_RO 4M {
+			RO_VPD(PRESERVE) 16K
+			RO_GSCVD 8K
+			RO_SECTION {
+				FMAP 2K
+				RO_FRID 64
+				GBB@4K 12K
+				COREBOOT(CBFS)
+			}
+		}
+	}
+}