generic-4.19: Backport spi-nand support for GigaDevice A/E

generic-4.19: Backport spi-nand support for GigaDevice A/E

This patch backports verbatim the commits from Linux 5.0 and 5.1
that implemented support for GigaDevice SPI NAND A and E variants.

Supported only in Linux 4.19 and later as based on the upstream
drivers/mtd/nand/spi/ framework.

mtd-spinand-add-support-for-GigaDevice-GD5FxGQ4xA.patch
commit c93c613214ac (5.0)

mtd-spinand-Add-support-for-GigaDevice-GD5F1GQ4UExxG.patch
commit c40c7a990a46 (5.1)

Run-tested-on: GL.iNet AR750S

Signed-off-by: Jeff Kletsky <git-commits@allycomm.com>