.gitignore: ignore *.swo and option *.roms

Change-Id: I7403f548bae918ca813a9295bfb095a7c4c51e21
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Reviewed-on: https://review.coreboot.org/15220
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/.gitignore b/.gitignore
index 5383e11..2ecbb51 100644
--- a/.gitignore
+++ b/.gitignore
@@ -58,7 +58,8 @@
 *.o
 *.out
 *.pyc
-*.swp
+*.sw[po]
+/*.rom
 
 # Development friendly files
 tags