ARM: OMAP3+: SmartReflex: Fix status masking in ERRCONFIG register

ERRCONFIG register has status bits that were intended not to
be destroyed by bad modification. We cleanup and simplify the
handling the status in the modify path.

Reported-by: Vincent Bour <v-bour@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>