Fix xtrpow2 test vector for BLS383 curve
Fix xtrpow2 test vector for BLS383 curve

milagro-crypto/milagro-crypto-c,miracl/milagro-crypto-c,miracl/milagro-crypto-c,miracl/milagro-crypto-c,milagro-crypto/milagro-crypto-c,miracl/milagro-crypto-c,milagro-crypto/milagro-crypto-c,miracl/milagro-crypto-c,milagro-crypto/milagro-crypto-c