xen/arm: Drop support of platform where GICH_LR_HW is not working correctly

xen/arm: Drop support of platform where GICH_LR_HW is not working correctly

Until recently, a maintenance IRQ was requested for any IRQ injected to
the guest on x-gene platform.

The commit 50dcb3de603927db2fd87ba09e29c817415aaa44 "xen: arm: X-Gene Storm
check GIC DIST address for EOI quirk" disable the quirk for boards using
the new firmware.

It is known that the quirk is fragile and cause performance regression.
Given that firmware is available for people having the board, I think
we can request the user to upgrade to the latest version.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Cc: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Acked-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>