net: allwinner: remove redundant irqsave and irqrestore in hardIRQ

The comment "holders of db->lock must always block IRQs" and related
code to do irqsave and irqrestore don't make sense since we are in a
IRQ-disabled hardIRQ context.

Cc: Maxime Ripard <mripard@kernel.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>