arm: ls1021a: Ensure LS1021 ARM Generic Timer CompareValue Set 64-bit

arm: ls1021a: Ensure LS1021 ARM Generic Timer CompareValue Set 64-bit

This patch addresses a problem mentioned recently on this mailing list:
[1].

In that posting a LS1021 based system was locking up at about 5 minutes
after boot, but the problem was mysteriously related to the toolchain
used for building u-boot.  Debugging the problem reveals a stuck
interrupt 29 on the GIC.

It appears Freescale's LS1021 support in u-boot erroneously sets the
64-bit ARM generic PL1 physical time CompareValue register to all-ones
with a 32-bit value.  This causes the timer compare to fire 344 seconds
after u-boot configures it.  Depending on how fast u-boot gets the
kernel booted, this amounts to about 5-minutes of Linux uptime before
locking up.

Apparently the bug is masked by some toolchains.  Perhaps this is
explained by default compiler options, word sizes, or binutils versions.
At any rate this patch makes the manipulation explicitly 64-bit which
alleviates the issue.

[1]
https://lists.yoctoproject.org/pipermail/meta-freescale/2015-June/014400.html

Signed-off-by: Chris Kilgour <techie@whiterocker.com>
Signed-off-by: Alison Wang <alison.wang@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>