haven: rm: Remove pr_err on get_vmid

If RM is not set up, drivers such as ion may be frequently calling
hh_rm_get_vmid and causing a console message that a VMID could not be
found. Drivers should be correctly handling the error case, so remove
the pr_err here to not fill console messages.

Change-Id: I2026d9481b6d58a89fb2f546bf76b29566e5f3d7
Signed-off-by: Elliot Berman <eberman@codeaurora.org>