drivers: qcom: Rename MSM_BOOT_TIME_MARKER

Prefix MSM_BOOT_TIME_MARKER with QGKI to differentiate
it as a vendor-specific config.

Change-Id: Icf369a4b217722d997706d30ffaceaf08b3e8ee1
Signed-off-by: Shreyas K K <shrekk@codeaurora.org>