brcmsmac: remove set but not used variables

brcmsmac: remove set but not used variables

drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c:841:7: warning: variable free_pdu set but not used [-Wunused-but-set-variable]
drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c:842:30: warning: variable tx_rts_count set but not used [-Wunused-but-set-variable]
drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c:842:6: warning: variable tx_rts set but not used [-Wunused-but-set-variable]
drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c:843:7: warning: variable totlen set but not used [-Wunused-but-set-variable]

They are never used, so can be removed.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>