When using `make M=/path/to/driver modules` to build a module, file
Module.symvers will be created in that directory, so it's better to
ignore it in all directories.

Slightly reordered, let specific file names behind general ones.

Cc: Andrew Morton <[email protected]>
Cc: Kyungsik Lee <[email protected]>
Cc: Markus Trippelsdorf <[email protected]>
Signed-off-by: Zhao, Gang <[email protected]>
Signed-off-by: Michal Marek <[email protected]>