drivers: memc: memc_mcux_flexspi: correctly handle multi-device usage

When multiple devices are used, the FLEXSPI will place their address
spaces sequentially (based on the chip select port used). Additionally,
each device must use different sections of the FLEXSPI LUT table.

Fix the following calculation issues with multi-device usage:
- correct calculation of LUT sequence indices for AHB commands
- correctly add address and sequence offset when submitting FLEXSPI IP
  transfer

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>