x86: Cleanup cpu-features-offsets.sym

Remove the unused macros.  There is no code changes in libc.so nor
ld.so on i686 and x86-64.

	* sysdeps/x86/cpu-features-offsets.sym
	(rtld_global_ro_offsetof): Removed.
	(CPU_FEATURES_SIZE): Likewise.
	(CPUID_OFFSET): Likewise.
	(CPUID_SIZE): Likewise.
	(CPUID_EAX_OFFSET): Likewise.
	(CPUID_EBX_OFFSET): Likewise.
	(CPUID_ECX_OFFSET): Likewise.
	(CPUID_EDX_OFFSET): Likewise.
	(FAMILY_OFFSET): Likewise.
	(MODEL_OFFSET): Likewise.
	(FEATURE_OFFSET): Likewise.
	(FEATURE_SIZ): Likewise.
	(COMMON_CPUID_INDEX_1): Likewise.
	(COMMON_CPUID_INDEX_7): Likewise.
	(FEATURE_INDEX_1): Likewise.
	(RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET): Updated.