radeon: Remove useless quirk for zx1/FireGL X1 combo introduced with fdo #7770

Removes useless quirk a7f465f73363fce409870f62173d518b1bc02ae6 introduced with
fdo #7770 as a failed attempt to minimize stability issues with hp zx1 chipset/
ATI FireGL X1 graphics adapter configuration
(see http://marc.info/?l=linux-ia64&m=140077543819871&w=2 for details/reason)

Signed-off-by: Émeric MASCHINO <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/radeon/radeon_agp.c

···
 	/* ATI Host Bridge / RV280 [M9+] Needs AGPMode 1 (phoronix forum) */
 	{ PCI_VENDOR_ID_ATI, 0xcbb2, PCI_VENDOR_ID_ATI, 0x5c61,
 		PCI_VENDOR_ID_SONY, 0x8175, 1},
-	/* HP Host Bridge / R300 [FireGL X1] Needs AGPMode 2 (fdo #7770) */
-	{ PCI_VENDOR_ID_HP, 0x122e, PCI_VENDOR_ID_ATI, 0x4e47,
-		PCI_VENDOR_ID_ATI, 0x0152, 2},
 	{ 0, 0, 0, 0, 0, 0, 0 },
 };
 #endif