mboxd: Rename flash files

Change-Id: Icfe9d61775a198c5a0f8227bf5d6c4b7f11aeec3
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/Makefile.am b/Makefile.am
index fa086da..5df4b95 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -17,7 +17,7 @@
 if VIRTUAL_PNOR_ENABLED
 include vpnor/Makefile.am.include
 else
-mboxd_SOURCES += mboxd_flash.c \
+mboxd_SOURCES += flash.c \
 	mboxd_lpc_reset.c
 endif