x86/cpu: Remove unused !CONFIG_X86_TSC code

x86/cpu: Remove unused !CONFIG_X86_TSC code

Now that the Kconfig space always enables CONFIG_X86_TSC (on x86),
remove !CONFIG_X86_TSC code from the x86 arch code.

We still keep the Kconfig option to catch any eventual code still
pending in maintainer or non-mainline trees, plus some drivers
have raw TSC timestamping hacks that use CONFIG_X86_TSC.

It's also still possible to disable TSC support runtime.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ahmed S . Darwish <darwi@linutronix.de>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250425084216.3913608-13-mingo@kernel.org