arch/powerpc/sysdev/fsl_rio.c: correct IECSR register clear value

arch/powerpc/sysdev/fsl_rio.c: correct IECSR register clear value

commit 671ee7f0ce62e4b991b47fcf1c161c3f710dabbc upstream.

This bug causes the IECSR register clear failure.  In this case, the RETE
(retry error threshold exceeded) interrupt will be generated and cannot be
cleared.  So the related ISR may be called persistently.

The RETE bit in IECSR is cleared by writing a 1 to it.

Signed-off-by: Liu Gang <Gang.Liu@freescale.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>