perf: starfive: fix 64-bit only COMPILE_TEST condition

ARCH_STARFIVE is not restricted to 64-bit platforms, so while Will's
addition of a 64-bit only condition satisfied the build robots doing
COMPILE_TEST builds, Palmer ran into the same problems with writeq()
being undefined during regular rv32 builds.

Promote the dependency on 64-bit to its own `depends on` so that the
driver can never be included in 32-bit builds.

Reported-by: Palmer Dabbelt <palmer@rivosinc.com>
Fixes: c2b24812 ("perf: starfive: Add StarLink PMU support")
Fixes: f0dbc6d0 ("perf: starfive: Only allow COMPILE_TEST for 64-bit architectures")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Ji Sheng Teoh <jisheng.teoh@starfivetech.com>
Acked-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Link: https://lore.kernel.org/r/20240318-emphatic-rally-f177a4fe1bdc@spud


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>