Draft: spi: stm32-qspi: Fix wait_cmd timeout in APM mode

In APM mode calling stm32_qspi_wait_cmd() leads to a timeout. The reason for this is that stm32_qspi_wait_cmd() requires the TCF/TEF flags to be set to finish. In APM mode these flags are not used. Currently it is working for most cases because the TCF/TEF flags are set by a previous command and not cleared when the command finishes or a new command is started.

Using two flashes and doing data transfers simoutanously on them triggers situations where the previous command doesn't finish with TCF flag set. Then the call to stm32_qspi_wait_cmd() leads to a timeout and e.g. into a read only UBI file system.