Fix a leaked Storage Variable.

Phabric:	D981
Submitted by:	myself
Reported by:	Coverity
CID:		1248848
Reworked by:	kevlo
Reviewed by:	marcel, davide, ray, kevlo
Approved by:	marcel, kevlo
Return BUS_PROBE_DEFAULT instead of BUS_PROBE_VENDOR or 0 for in-tree
driver.  This change was verified by Microsoft.
- Add inttypes.h and stdint.h in lieu of int_limits.h from NetBSD
- Use #include "h_macros.h" instead of relative path analog

Sponsored by: EMC / Isilon Storage Division
- Mark signo __unused in the signal handler function
- Effectively #if 0 out some code that does not fail on FreeBSD

In collaboration with: pho
Sponsored by: EMC / Isilon Storage Division
amd64: make uiomove_fromphys functional for pages not mapped by the DMAP

Place the code introduced in r268660 into a separate function that can be
called from uiomove_fromphys. Instead of pre-allocating two KVA pages use
vmem_alloc to allocate them on demand when needed. This prevents blocking if
a page fault is taken while physical addresses from outside the DMAP are
used, since the lock is now removed.

Also introduce a safety catch in PHYS_TO_DMAP and DMAP_TO_PHYS.

Sponsored by: Citrix Systems R&D
Reviewed by:		kib
Differential Revision:	https://reviews.freebsd.org/D947

amd64/amd64/pmap.c:
 - Factor out the code to deal with non DMAP addresses from pmap_copy_pages
   and place it in pmap_map_io_transient.
 - Change the code to use vmem_alloc instead of a set of pre-allocated
   pages.
 - Use pmap_qenter and don't pin the thread if there can be page faults.

amd64/amd64/uio_machdep.c:
 - Use pmap_map_io_transient in order to correctly deal with physical
   addresses not covered by the DMAP.

amd64/include/pmap.h:
 - Add the prototypes for the new functions.

amd64/include/vmparam.h:
 - Add safety catches to make sure PHYS_TO_DMAP and DMAP_TO_PHYS are only
   used with addresses covered by the DMAP.