remoteproc: qcom: q6v5-pil: fix modem hang on SDM845 after axis2 clk unvote

GCC_MSS_AXIS2 clock is used for disabling boot IMEM (a part of
AP boot up). With Boot IMEM disable now a part TZ/ATF, AXIS2
clock is no longer required post AP boot up and expected to
remain untouched. However if the clock is turned ON after Q6
is brought out of reset and later turned off, it results in
modem hang. When Q6 attempts a power collapse the internal
handshaking to check if AXIS2 is idle never goes through since
it is turned off preventing the RSC from getting triggered,
leaving modem in a funky state. Hence removing AXIS2 clk
enable/disable from the driver.

Reported-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>