monitor: Prevent sign-extension of 32-bit addresses printed by info tlb

This is the same fix that was recently applied to info mem.  Before
this change, info tlb output looked like:

ffffffffffffc000: 000000000fffc000 --------W
ffffffffffffd000: 000000000fffd000 --------W
ffffffffffffe000: 000000000fffe000 --------W
fffffffffffff000: 000000000ffff000 --------W

With this change, it looks like

00000000ffffc000: 000000000fffc000 --------W
00000000ffffd000: 000000000fffd000 --------W
00000000ffffe000: 000000000fffe000 --------W
00000000fffff000: 000000000ffff000 --------W

Signed-off-by: Austin Clements <amdragon@mit.edu>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
