scripts/mkimg.arm.sh: fix regression

scripts/mkimg.arm.sh

@@ -55,6 +55,7 @@ build_rpi_config() {
 }
 
 section_rpi_config() {
+	[ "$hostname" = "rpi" ] || return 0
 	build_section rpi_config $( (rpi_gen_cmdline ; rpi_gen_config) | checksum )
 	build_section rpi_blobs
 }