Fixed incorrect usage of vshuf.b instruction

Fixed incorrect usage of vshuf.b instruction

In the definition of the latest revised LoongArch64 vector instruction manual,
it is clearly pointed out that the undefined upper three bits of each byte in
the control register of the vshuf.b instruction should not be used, otherwise
uncertain results may be obtained. Therefore, it is necessary to correct the
use of the vshuf.b instruction in the existing vpaes-loongarch64.pl code to
avoid erroneous calculation results in future LoongArch64 processors.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21530)