I was going to complete the quest where you have to recover the platinum chip from Benny at Caesar's tent, the problem I have is that when I try to approach tent, the legion becomes hostile towards me and I have "mixed" for my rep with them. What gives? I never encountered this glitch before and Benny doesn't show up at the location either (which I know happens and frustrating) which prevents me from finishing the quest.

Bump

It doesn't prevent you from finishing the quest.

Fire Boone, if he is a companion.
Wear faction armour for Legion
Kill them all and head to the Fort via the boat yourself (If you aren't doing a Legion playthrough)

Problem is, no one has the platinum chip I can't complete the house quest part where you upgrade the sercutitron army, which I am doing so I can get the wild card ending with yes man.

I think I did something wrong cuz isn't Caesar suppose to have it if you kill him? Or maybe glitched somehow?

Location:
The platinum chip can be obtained by killing Benny. It is also possible to obtain the chip by either working with or killing http://fallout.wikia.com/wiki/Caesar.

You could try this:
It's possible to obtain 2 Platinum chips. First obtain the first one from http://fallout.wikia.com/wiki/Benny. Then visit http://fallout.wikia.com/wiki/Caesar. Then exit the premises of http://fallout.wikia.com/wiki/The_Fort and become vilified by http://fallout.wikia.com/wiki/Caesar%27s_Legion (or any reputation that makes them hostile). Then pay another visit to Caesar and kill him. The second Platinum chip can now be looted from his corpse.