aarch64: Remove HWCAP_CPUID from HWCAP_IMPORTANT

This partially reverts

commit f82e9672
Author:     Siddhesh Poyarekar <siddhesh@sourceware.org>

    aarch64: Allow overriding HWCAP_CPUID feature check using HWCAP_MASK

The idea was to make it possible to disable cpuid based ifunc resolution
in glibc by changing the hwcap mask which the user could already control.

However the hwcap mask has an orthogonal role: it specifies additional
library search paths for the dynamic linker.  So "cpuid" got added to
the search paths when it was set in the default mask (HWCAP_IMPORTANT),
which is not useful behaviour, the hwcap masking should not be reused
in the cpu features code.

Meanwhile there is a tunable to set the cpu explicitly so it is possible
to disable the cpuid based dispatch without using a hwcap mask:

  GLIBC_TUNABLES=glibc.tune.cpu=generic

	* sysdeps/unix/sysv/linux/aarch64/cpu-features.c (init_cpu_features):
	Use dl_hwcap without masking.
	* sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h (HWCAP_IMPORTANT):
	Remove HWCAP_CPUID.

(cherry picked from commit d0cd7980)