mtd: maps: remove AMD Élan specific drivers

mtd: maps: remove AMD Élan specific drivers

There were four MTD maps drivers that were used with AMD Élan SoCs.
Since 486-class CPU support was removed in commit 8b793a92d862 ("x86/cpu:
Remove M486/M486SX/ELAN support"), it is no longer possible to actually
use these. Three of them have already been removed, so remove the
remaining driver entirely.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[Miquel Raynal: Only NETtel was still in the tree, adapt the patch and the commit log]
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>