crypto: ecc - Add nbits field to ecc_curve structure

Add the number of bits a curve has to the ecc_curve definition to be able
to derive the number of bytes a curve requires for its coordinates from it.
It also allows one to identify a curve by its particular size. Set the
number of bits on all curve definitions.

Tested-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Vitaly Chikunov <vt@altlinux.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/ecc_curve_defs.h

@@ -17,6 +17,7 @@ static u64 nist_p192_b[] = { 0xFEB8DEECC146B9B1ull, 0x0FA7E9AB72243049ull,
 				0x64210519E59C80E7ull };
 static struct ecc_curve nist_p192 = {
 	.name = "nist_192",
+	.nbits = 192,
 	.g = {
 		.x = nist_p192_g_x,
 		.y = nist_p192_g_y,
@@ -43,6 +44,7 @@ static u64 nist_p256_b[] = { 0x3BCE3C3E27D2604Bull, 0x651D06B0CC53B0F6ull,
 				0xB3EBBD55769886BCull, 0x5AC635D8AA3A93E7ull };
 static struct ecc_curve nist_p256 = {
 	.name = "nist_256",
+	.nbits = 256,
 	.g = {
 		.x = nist_p256_g_x,
 		.y = nist_p256_g_y,
@@ -75,6 +77,7 @@ static u64 nist_p384_b[] = { 0x2a85c8edd3ec2aefull, 0xc656398d8a2ed19dull,
 				0x988e056be3f82d19ull, 0xb3312fa7e23ee7e4ull };
 static struct ecc_curve nist_p384 = {
 	.name = "nist_384",
+	.nbits = 384,
 	.g = {
 		.x = nist_p384_g_x,
 		.y = nist_p384_g_y,
@@ -95,6 +98,7 @@ static u64 curve25519_a[] = { 0x000000000001DB41, 0x0000000000000000,
 				0x0000000000000000, 0x0000000000000000 };
 static const struct ecc_curve ecc_25519 = {
 	.name = "curve25519",
+	.nbits = 255,
 	.g = {
 		.x = curve25519_g_x,
 		.ndigits = 4,