staging: mt7621-pci: Do not initialise statics to 0

Remove initialisation for static global variable to fix checkpatch issue.
ERROR: do not initialise statics to 0

Signed-off-by: Mamta Shukla <mamtashukla555@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>