ARM: dts: msm: add IPA keepalive dev_bw device for sdxprairie

Add a keepalive governor for IPA core clock since the
gcc_aggre_noc_tbu2_clk moved under IPA clock domain. This is a
workaround for a TCU hang that occurs when it tries to invalidate
the IPA TBU during non-IPA usecases while the IPA clock is off.

Change-Id: If42c18673ca93d1b6114ee924cf9aac391db35e7
Signed-off-by: David Dai <daidavid1@codeaurora.org>