Both runtime_suspend_v3_hw() and runtime_resume_v3_hw() do nothing else but
invoke suspend_v3_hw() and resume_v3_hw() respectively. This is the case of
unnecessary function calls. To use those functions for runtime pm as well,
simply use UNIVERSAL_DEV_PM_OPS.

make -j$(nproc) W=1, with CONFIG_PM disabled, throws '-Wunused-function'
warning for runtime_suspend_v3_hw() and runtime_resume_v3_hw(). After
dropping those function definitions, the warning was thrown for
suspend_v3_hw() and resume_v3_hw(). Hence, mark them as '__maybe_unused'.

Link: https://lore.kernel.org/r/20201102164730.324035-15-vaibhavgupta40@gmail.comSigned-off-by: NVaibhav Gupta <vaibhavgupta40@gmail.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>