staging: mt7621-pci: Add spaces around '&'

Add spaces around '&' to fix checkpatch issue.
CHECK: spaces preferred around that '&' (ctx:VxV)

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