ARM: msm: add 64-bit IO accessor support

This is a snapshot of the 64-bit IO accessor support as of msm-3.10
commit

'commit acdce027751d5a7 ("Merge defconfig: arm64: Enable
ONESHOT_SYNC for msm8994")'

Change-Id: Idc857357a87ba91cdb7a69deeaf05aa8d5d13628
Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
[sramana: fixed merge conflicts]
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>