mtd: spi-nor: spansion: add MCP support in set_octal_dtr()

Infineon multi-chip package (MCP) devices require the Octal DTR
configuraion to be set on each die. We can access to configuration
registers in each die by using params->n_dice and params->vreg_offset[]
populated from SFDP. Add MCP support in set_octal_dtr().

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Link: https://lore.kernel.org/r/20230726075257.12985-7-tudor.ambarus@linaro.org


Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>