spi: cadence_qspi_apb: Use 32 bit indirect write transaction when possible

According to Section 11.15.4.9.2 Indirect Write Controller of K2G SoC
TRM SPRUHY8D[1], the external master is only permitted to issue 32-bit
data interface writes until the last word of an indirect transfer
otherwise indirect writes is known to fails sometimes. So, make sure
that QSPI indirect writes are 32 bit sized except for the last write. If
the txbuf is unaligned then use bounce buffer to avoid data aborts.

So, now that the driver uses bounce_buffer, enable CONFIG_BOUNCE_BUFFER
for all boards that use Cadence QSPI driver.

[1]www.ti.com/lit/ug/spruhy8d/spruhy8d.pdf

Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Jagan Teki <jagan@openedev.com>