iommu/msm: Print context name instead of device name

When probing the context devices, dev_info already prints
the device name, so printing it again is redundant. The
context name is more useful anyway, so print this instead.

Change-Id: Ibe2e33501baa1fd53f6ff45943226377eb61fd7e
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>