ARM: 8563/1: fix demoting HWCAP_SWP

Commit b8c9592b "ARM: 8318/1: treat CPU feature register fields as signed
quantities" accidentally altered cpuid register used to demote
HWCAP_SWP.
ARM ARM says that SyncPrim_instrs bits in ID_ISAR3 should be used with
SynchPrim_instrs_frac from ID_ISAR4. So, follow this rule.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>