bcma: remove two unused variables

drivers/bcma/driver_mips.c:70:18: warning:
 ipsflag_irq_shift defined but not used [-Wunused-const-variable=]
drivers/bcma/driver_mips.c:62:18: warning:
 ipsflag_irq_mask defined but not used [-Wunused-const-variable=]

They are never used, so can be removed.

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