msm: bufmgr: Fix crash due to improper use of compat_ptr

Do not use compat_ptr for the ioctl argument because it is already
converted into 64bit pointer by the framework. Doing so may cause
a crash.

Change-Id: I8b0f2bbe1083fc01836e0f52601b79d31ed0a600
Signed-off-by: Aditya Jonnalagadda <ajonnala@codeaurora.org>