drm/msm: Pass interrupt status to a5xx_rbbm_err_irq()

The interrupt status was being cleared before processing the handlers.
a5xx_rbbm_err_irq() was checking the interrupt status again, which would
likely turn out bad because the interrupt status would be 0 (or at least
different). Pass the original status to the function instead.

Also, skip clearing RBBM_AHB_ERROR from the interrupt status. The interrupt
will keep firing until the error source is cleared.  Skip the clear to
avoid a storm until the error is cleared in a5xx_rbbm_err_irq().

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>