To enable AARCH64 native instruction support for Openssl,
some interfaces must be implemented. OPENSSL_rdtsc() requests
an access to a counter to get some non-trusted entropy.
Add ArmReadCntPctReg() to read system count.
A similar ArmReadCntPct() function is available in the ArmPkg,
but the CryptoPkg where OPENSSL_rdtsc will reside cannot rely
on the ArmPkg.
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
