soc: qcom: Add driver to print xbl log on console from fs

Add driver to capture xbl log from reserved memory region
and print on console when user requests.

Use cat /sys/module/xbl_log/xbl_log to see xbl log.

Change-Id: I5d34a4be63244f354ce70cfac8df2724b6a0537b
Signed-off-by: Vinay Sudra <vsudra@codeaurora.org>