roms: simplify build_roms()

cbcfg is already a global variable, so there's no reason
to set it again at the start of this function.

remove the check for whether the given coreboot config
exists, to the calling function instead of build_roms().

Signed-off-by: Leah Rowe <leah@libreboot.org>

script/roms

@@ -184,16 +184,13 @@ build_board()
 			    [ "$displaymode" != "txtmode" ] && continue
 			cbcfg="$targetdir/config/${initmode}_$displaymode"
 			[ "$initmode" = "normal" ] && cbcfg="${cbcfg%_*}"
-			build_roms "$cbcfg"; x_ rm -f "$cbrom"
+			e "$cbcfg" f not || build_roms; x_ rm -f "$cbrom"
 		done
 	done
 }
 
 build_roms()
 {
-	cbcfg="$1"
-	e "$cbcfg" f not && return 0
-
 	x_ ./update trees -b coreboot $board
 
 	_cbrom="elf/coreboot_nopayload_DO_NOT_FLASH"