dev-arm: Mask el2_watchdog in VExpressFastmodel platform
dev-arm: Mask el2_watchdog in VExpressFastmodel platform

el2_watchdog depends on SystemCounter. However, we have mask
system_counter in the platform. We should also mask the el2_watchdog
accordingly.

Change-Id: I2ed774549272438d654e0573ffe9f482a6659d37
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55306
Reviewed-by: Gabe Black <d3e8afea784ab4a50a2dbf9149d2eaa8478e1cbc@gmail.com>
Reviewed-by: Giacomo Travaglini <8eef13a4f970e2e9372c8d26ad0737b760f99c02@arm.com>
Maintainer: Giacomo Travaglini <8eef13a4f970e2e9372c8d26ad0737b760f99c02@arm.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/56248
Reviewed-by: Jason Lowe-Power <92de577f37050ad05b60626d2f17913f40dcb1a2@gmail.com>
Maintainer: Jason Lowe-Power <92de577f37050ad05b60626d2f17913f40dcb1a2@gmail.com>

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