x86/cpufeatures: Rename X86_FEATURE_FAST_CPPC to have AMD prefix

This feature is an AMD unique feature of some processors, so put
AMD into the name.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20241025171459.1093-2-mario.limonciello@amd.com