[PATCH] smc91x: fix bank mismatch

The smc91x driver relies upon register bank 2 being selected whenever
the interrupt handler is called.  This isn't always so, especially if
we have a link change event during PHY configuration.

This results in register bank 0 being selected when the interrupt
handler is called, causing the wrong registers to be read for the
IRQ mask and status.  In turn, this causes us to spin with a
permanently asserted IRQ.

The patch ensures that smc_phy_configure always exits with register
bank 2 selected.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>