msm: Change vendor name from 'qcom' to 'qti' for imem

As we have recently moved to use 'qti' as vendor name reflect
that change for all imem related code.

Change-Id: I544c9bc2bd96b1874d35378c2a454390e9b2e92b
Signed-off-by: Kumar Gala <galak@codeaurora.org>