ARM: 5909/1: ARM: Correct the FPSCR bits setting when raising exceptions

Commit c98929c07a removed the clearing of the FPSCR[31:28] bits from the
vfp_raise_exceptions() function and the new bits are or'ed with the old
FPSCR bits leading to unexpected results (the original commit was
referring to the cumulative bits - FPSCR[4:0]).

CRs-fixed: 246571

Change-Id: I7119cf175dc572783d27d2953e9f4ae712b8dee5
Reported-by: Tom Hameenanttila <tmhameen@marvell.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
Signed-off-by: Sireesha <c_schadi@qualcomm.com>