mmc: sh_mmcif: process error interrupts first

If an interrupt is coming with both error and data completion status bits
set, it has to be handled as an error interrupt, for which error interrupts
have to be processed first. The current version of the driver on the
contrary doesn't recognise such interrupts as an error event, which leads
to data corruption and breaks the error recovery.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>