msm: lpm-levels: Add kernel parameter to disable sleep

By default, the lpm levels are disabled. For debug scenarios, it is
beneficial to start the device with low power modes disabled. Provide a
module parameter to override the default behavior

Change-Id: I79c5fa665fdf2b3d6331e2c51e22a5990ba5bf1f
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>