aarch64: Use 64-bit variable to access the special registers

aarch64: Use 64-bit variable to access the special registers

clang issues:

  error: value size does not match register size specified by the
  constraint and modifier [-Werror,-Wasm-operand-widths]

while tryng to use 32 bit variables with 'mrs' to get/set the
fpsr, dczid_el0, and ctr.