ARM: dts: msm: Fix boolean property misuse

In the msm_serial_hs driver bindings,
'qcom,inject-rx-on-wakeup' is a boolean property, meaning
that there is no need to explicitly give it a value. The
presence of the property alone is enough to indicate that
the corresponding value shall be treated as 'true'.

Change-Id: Ib2733561d20e83a883516986ff84f04de8b5d9d3
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>