target/hexagon: initialize deferred sreg-write temps to current value

Unconditionally allocate and initialize the temp to the sreg's current value for every logged sreg write, rather than only allocating when need_commit is set or the register is SSR. Without this, reading a deferred sreg write within the same packet before it is committed can observe an uninitialized temp instead of the register's pre-packet value. Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com> Signed-off-by: Brian Cain <brian.cain@oss.qualcomm.com>