power: modify HAS_STATE_SLEEP_ Kconfig options

Add SYS_POWER_ prefix to HAS_STATE_SLEEP_, HAS_STATE_DEEP_SLEEP_
options to align them with names of power states they control.
Following is a detailed list of string replacements used:
s/HAS_STATE_SLEEP_(\d)/HAS_SYS_POWER_STATE_SLEEP_$1/
s/HAS_STATE_DEEP_SLEEP_(\d)/HAS_SYS_POWER_STATE_DEEP_SLEEP_$1/

Signed-off-by: Piotr Mienkowski <piotr.mienkowski@gmail.com>