HID: qvr: Fix for potential heap buffer overflow

Value of sensor->calib_data_len could be changed between
the reads causing potential heap buffer overflow.
When a 0 length is passed to kzalloc, non-NULL pointer
is returned, but this pointer is invalid.

Change-Id: Ie6ed76f63f7a433728e2292222ba9716c3a02635
Signed-off-by: rbandi <rohitbandi@codeaurora.org>