[PARISC] Delete arch/parisc/mm/kmap.c again

I deleted this file from 2.4 5 years ago.  Unfortunately, that change
never got merged to Linus and so when we switched to 2.5 it came back
and nobody noticed.  It's never been built in 2.5/2.6 as it was never
in the Makefile.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>