v4.4-stable: GPMI nand controller broken

[Sascha Hauer]

The following went into v4.4.120:

197190bc5c48 mtd: nand: gpmi: Fix failure when a erased page has a bitflip at BBM

This patch was backported to far for the stable tree. It only makes sense
(and only works) together with:

bd2e778c9ee3 gpmi-nand: Handle ECC Errors in erased pages

which first appeared in v4.7.

So either we revert 197190bc5c48 on the v4.4 stable tree or we apply the
attached patch which is a backport of bd2e778c9ee3 for v4.4.

I don't know which solution is prefered, personally I would prefer
applying the attached patch which is also a bugfix. Without it erased
pages may not be handled properly.

Sascha

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