htab_bolt_mapping() takes a vstart and pstart parameter, but all but one of
its callers actually pass it vstart and vstart. Luckily before it passes
paddr (calculated from paddr) to the hpte_insert routines it calls
virt_to_abs() (aka. __pa()) on the address, so there isn't actually a bug.

map_io_page() however does pass pstart properly, so currently it's broken
AFAICT because we're calling __pa(paddr) which will get us something very
large. Presumably no one's calling map_io_page() in the right context.

Anyway, change htab_bolt_mapping() callers to properly pass pstart, and then
use it properly in htab_bolt_mapping(), ie. don't call __pa() on it again.

Booted on p5 LPAR, iSeries and Power3.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>