For TI12xx and newer, clear register 0x84. This is the "Multimedia"

For TI12xx and newer, clear register 0x84.  This is the "Multimedia"
register.  It enables Zoom Video.  It appears that on at least one
card that Monzoon is using sets these bits by default.  Nothing works
when these bits are set, everything works when they are clear.

Add commentary on some of the ti bits.  Make code a little clearer.
Also remove a call to pcic_pci_pd6729 which was prematurely added in
the last commit.