perf: MARVELL_CN10K_TAD_PMU should depend on ARCH_THUNDER

perf: MARVELL_CN10K_TAD_PMU should depend on ARCH_THUNDER

The Marvell CN10K Last-Level cache Tag-and-data Units (LLC-TAD)
performance monitor is only present on Marvell CN10K SoCs.  Hence add a
dependency on ARCH_THUNDER, to prevent asking the user about this driver
when configuring a kernel without Cavium Thunder (incl. Marvell CN10K)
SoC support.

Fixes: 036a7584bede ("drivers: perf: Add LLC-TAD perf counter support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/b4662a2c767d04cca19417e0c845edea2da262ad.1641995941.git.geert+renesas@glider.be
Signed-off-by: Will Deacon <will@kernel.org>