mtd: nand: denali: remove detect_partition_feature()

The denali->fwblks is set by detect_partition_feature(), but it is
not referenced from anywhere.  That means the struct member fwblks
and the whole of detect_partition_feature() are unneeded.

The comment block implies this function is only for Intel platforms.
I found drivers/staging/spectra used to exist, but it was deleted by
commit be7f39c5 ("Staging: delete spectra driver") 5 years ago.

So, I guess nobody would need this function any more.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>