ARM: 8041/1: pj4: fix cpu_is_pj4 check

ARM: 8041/1: pj4: fix cpu_is_pj4 check

Commit fdb487f5c961b94486a78fa61fa28b8eff1954ab
  ("ARM: 8015/1: Add cpu_is_pj4 to distinguish PJ4 because it
    has some differences with V7")
introduced a cpuid check for Marvell PJ4 processors to fix a
regression caused by adding PJ4 based Marvell Dove into
multi_v7.

Unfortunately, this check is too narrow to catch PJ4 used on
Dove itself and breaks iWMMXt support.

This patch therefore relaxes the cpuid mask to match both PJ4
and PJ4B. Also, rework the given comment about PJ4/PJ4B
modifications to be a little bit more specific about the
differences.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>