RMX1921: sepolicy: allow qti_init_shell to change watermark_scale_factor

* avc: denied { write } for comm="init.qcom.post_" name="watermark_scale_factor" dev="proc" ino=48744 scontext=u:r:qti_init_shell:s0 tcontext=u:object_r:proc_watermark_scale_factor:s0 tclass=file permissive=0

Signed-off-by: kaderbava <ksbava7325@gmail.com>