arm64: Add CNTVCT_EL0 cp15 AArch32 trap handler

Cntvct access was disabled by default, in
'commit 7b4edf24 ("clocksource: arch_timer: make
virtual counter access configurable"). There is a
trap handler added for user access using mrs instruction
in 'commit 9ce281d3 ("arm64: Add CNTVCT_EL0 trap
handler")' However, el0 running in AArch32 can try to
access cntvct using mrrc instruction. So, add a trap
handler to support that.

Change-Id: I788c03d87cd5a2d0e8d02da6662e2a1fb5e92827
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>