mtd: denali: add Denali controller configs to Kconfig

Commit 3eb3e72a (nand/denali: Adding Denali NAND driver support)
introduced some new options, and some of them were documented by
commit f9860cf0 (nand/denali: Document CONFIG symbols).

This commit allows users to enable/disable them via Kconfig
with more detailed help docs.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Chin Liang See <clsee@altera.com>
Cc: Scott Wood <scottwood@freescale.com>