input: bu21150: buffer touch frames

Some frames might be lost if user space cannot
get the frames in time. Buffer frames to avoid this.

Conflicts:
	drivers/input/touchscreen/bu21150.c

Change-Id: I46359f243d1065bb95cf0d13988ac181cf4f5454
Signed-off-by: Mohan Pallaka <mpallaka@codeaurora.org>
Signed-off-by: Bharat Pawar <bpawar@codeaurora.org>
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>