wl3501_cs: remove pedantic build warning

drivers/net/wireless/wl3501_cs.c: In function ‘wl3501_esbq_exec’:
drivers/net/wireless/wl3501_cs.c:387: warning: ‘tmp’ is used uninitialized in this function
drivers/net/wireless/wl3501_cs.c:384: note: ‘tmp’ was declared here

Signed-off-by: John W. Linville <linville@tuxdriver.com>