crypto: ecc - correct kernel-doc format

crypto: ecc - correct kernel-doc format

Fix all kernel-doc warnings in ecc.h:
- use correct kernel-doc format
- add some Returns: sections
- fix spelling and parameter names

Fixes these warnings:
Warning: include/crypto/internal/ecc.h:82 function parameter 'nbytes' not
 described in 'ecc_digits_from_bytes'
Warning: include/crypto/internal/ecc.h:82 function parameter 'out' not
 described in 'ecc_digits_from_bytes'
Warning: include/crypto/internal/ecc.h:95 No description found for return
 value of 'ecc_is_key_valid'
Warning: include/crypto/internal/ecc.h:110 No description found for return
 value of 'ecc_gen_privkey'
Warning: include/crypto/internal/ecc.h:124 No description found for return
 value of 'ecc_make_pub_key'
Warning: include/crypto/internal/ecc.h:143 No description found for return
 value of 'crypto_ecdh_shared_secret'
Warning: include/crypto/internal/ecc.h:182 No description found for return
 value of 'vli_is_zero'
Warning: include/crypto/internal/ecc.h:194 No description found for return
 value of 'vli_cmp'
Warning: include/crypto/internal/ecc.h:209 function parameter 'right' not
 described in 'vli_sub'
Warning: include/crypto/internal/ecc.h:271 expecting prototype for
 ecc_aloc_point(). Prototype was for ecc_alloc_point() instead
Warning: include/crypto/internal/ecc.h:287 function parameter 'point' not
 described in 'ecc_point_is_zero'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>