spi: spi-mem: Create a repeated address operation

spi: spi-mem: Create a repeated address operation

In octal DTR mode addresses may either be long enough to cover at least
two bytes (in which case the existing macro works), or otherwise for
single byte addresses, the byte must also be duplicated and sent twice:
on each front of the clock.

Create a macro for this common case.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>