staging: rtl8192u: Add space around binary operators

This patch fixes the file r8180_93cx6.c to avoid the checkpatch.pl warnings:

	CHECK: spaces preferred around that '<<' (ctx:VxV)
	CHECK: spaces preferred around that '-' (ctx:VxV)

Signed-off-by: Sumera Priyadarsini <sylphrenadin@gmail.com>
Link: https://lore.kernel.org/r/20190822193535.14357-1-sylphrenadin@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>