fs/nfsd: Delete invalid assignment statements in nfsd4_decode_exchange_id

READ_BUF(8);
dummy = be32_to_cpup(p++);
dummy = be32_to_cpup(p++);
...
READ_BUF(4);
dummy = be32_to_cpup(p++);

Assigning value to "dummy" here, but that stored value
is overwritten before it can be used.
At the same time READ_BUF() will re-update the pointer p.

delete invalid assignment statements
Signed-off-by: Nnixiaoming <nixiaoming@huawei.com>
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <trondmy@hammerspace.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4xdr.c

@@ -1390,10 +1390,8 @@ nfsd4_decode_exchange_id(struct nfsd4_compoundargs *argp,
 			p += XDR_QUADLEN(dummy);
 		}
 
-		/* ssp_window and ssp_num_gss_handles */
+		/* ignore ssp_window and ssp_num_gss_handles: */
 		READ_BUF(8);
-		dummy = be32_to_cpup(p++);
-		dummy = be32_to_cpup(p++);
 		break;
 	default:
 		goto xdr_error;