msm: boot_stats: Add snapshot of boot_stats driver

Add a snapshot of the msm boot_stats driver as of commit
acdce027751d5a7488b283f0ce3111f873a5816d (Merge "defconfig: arm64: Enable
ONESHOT_SYNC for msm8994")

Change-Id: Iee7ec288fe44606b468dc533bb4221f8d018b3cb
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
[abhimany: resolve trivial merge conflicts and add header file]
Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>