kbuild: ignore all generated files for make allmodconfig (x86_64)

With following patch we now ignore all generated files for
make allmodconfig for x86_64.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

drivers/atm/.gitignore

+# Ignore generated files
+fore200e_mkfirm
+fore200e_pca_fw.c
+pca200e.bin
+

sound/oss/.gitignore

+#Ignore generated files
+maui_boot.h
+pss_boot.h
+trix_boot.h