RMX1971: rootdir: use {up,down}_rate_limit_us

CAF replaced rate_limit_us with up_rate_limit_us and
down_rate_limit_us in msm-4.9 kernel with commit:

"ANDROID: cpufreq: schedutil: add up/down frequency transition rate limits"

Therefore, update the node in init.qcom.power.rc as well.

Signed-off-by: Chenyang Zhong <zhongcy95@gmail.com>
Signed-off-by: kaderbava <ksbava7325@gmail.com>