cifsd: Call smb2_set_err_rsp() in smb2_read/smb2_write error path

Call smb2_set_err_rsp() in smb2_read/smb2_write error path.

Signed-off-by: Marios Makassikis <mmakassikis@freebox.fr>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>