pxa2xx-ac97: fix displaying GSR after reset timeout

the variable gsr_bit is set in isr. It is however set to 0 and interrupts are
disabled prior to reset. Hence it doesn't make a lot of sense to show the
content of gsr_bit in case of a reset timeout.

Signed-off-by: Luotao Fu <l.fu@pengutronix.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>