[MTD] NAND: Fix ams-delta after core conversion

[Sergei Shtylyov]

Hello.

Sergei Shtylyov wrote:

>>The recent hwctrl core conversion for MTD NAND devices broke the Amstrad
>>Delta driver. This fixes it up and uses the existing control line
>>defines rather than unclear magic numbers.

>     Ugh, au1550nd.c also looks broken by this change. No time to fix now though...

   OTOH, it was too hasty conclusion. This driver overrides both select_chip 
and cmdfunc, so probably not. I'll try it somewhat later for real...

WBR, Sergei