mtd: spi-nor: Extract volatile register offset from SCCR map

mtd: spi-nor: Extract volatile register offset from SCCR map

In use of multi-chip devices, we need to access registers in each die for
configuration and status check. The number of dice in the device and
volatile register offsets for each die are essential to iterate register
access ops.

The volatile register offset for the first die resides in the 1st DWORD
of SCCR map. Allocate the table and copy the offset value.

The table may be allocated when the SCCR map for multi-chip is parsed.
Since we cannot assume SCCR parse is always in ahead of SCCR multi-chip,
we need to check if the table is already allocated or not.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Link: https://lore.kernel.org/r/e2cc39ad6e0e02dd8288c4def9bb201a3f564425.1680849425.git.Takahiro.Kuwano@infineon.com
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>