SecurityPkg/RngDxe: Add AArch64 RawAlgorithm support through ArmTrngLib

Bugzilla: 3668 (https://bugzilla.tianocore.org/show_bug.cgi?id=3668

)

RawAlgorithm is used to provide access to entropy that is suitable
for cryptographic applications. Therefore, add RawAlgorithm support
that provides access to entropy using the ArmTrngLib.

Also remove unused UefiBootServicesTableLib library inclusion
and Status variable.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Acked-by: Jiewen Yao <jiewen.yao@intel.com>