soc: mediatek: PMIC wrap: Fix register state machine handling

When the PMIC wrapper state machine has read a register it goes into the
"wait for valid clear" (vldclr) state. The state machine stays in this
state until the VLDCLR bit is written to. We should write this bit after
reading a register because the SCPSYS won't let the system go into
suspend as long as the state machine waits for valid clear.

Since now we never leave the state machine in vldclr state we no longer
have to check for this state on pwrap_read/pwrap_write entry and can
remove the corresponding code.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>