msm: kgsl: Remove support for IOCTL_KGSL_SHAREDMEM_FROM_VMALLOC

All userspace consumers should now be using IOCTL_KGSL_GPUMEM_ALLOC,
so we can safely remove this kludgy and deprecated code.  The structs
and #defines are left in the header to avoid breaking userspace and
to serve as a reminder of the way we were, but any use of
IOCTL_KGSL_SHAREMEM_FROM_VMALLOC will return -ENOTTY.

Change-Id: Ic0dedbad1460acfe28116ee2dbd75faa52b76857
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>