.gitignore: Add bzip2 compressed files

We can have bzip2 compressed images nowadays.
Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

.gitignore

@@ -25,6 +25,7 @@
 *.elf
 *.bin
 *.gz
+*.bz2
 *.lzma
 *.patch
 *.gcno