diag: Change IPC logging debug bit mask through debugfs

Diag driver uses IPC logging to log certain events in the driver.
Make the bit mask that governs which logs are being logged
configurable through debugfs.

Change-Id: Ieb1906992c8fcff9cffc2339323e0d7b10f3356f
Signed-off-by: Ravi Aravamudhan <aravamud@codeaurora.org>