mtd: spi-nor-core: Rework spansion_read_any_reg() to support Octal DTR mode

In Infineon multi-die package parts, we need to use Read Any Register op
to read status register in 2nd or further die. Infineon S28HS02GT is
dual-die package and supports Octal DTR interface. To support this,
spansion_read_any_reg() needs to be reworked. Implementation is similar
to existing read_sr() that already supports Octal DTR mode.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>