[ARM] 4629/1: Fix VFP emulation code to clear all exception flags of FPEXC

All exception flags of the FPEXC register must be cleared before
returning from exception code to user code, including FP2V and OFC.

Signed-off-by: Takashi Ohmasa <ohmasa.takashi@jp.panasonic.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>