LU-18822 build: fix symbol redeclaration error in socklnd_lib.c

LU-18822 build: fix symbol redeclaration error in socklnd_lib.c

This patch fixes the following symbol redeclaration errors
in socklnd_lib.c:

  lnet/klnds/socklnd/socklnd_lib.c: In function 'ksocknal_lib_recv_kiov':
  lnet/klnds/socklnd/socklnd_lib.c:314:23: error: 'scratchiov' redeclared as different kind of symbol
    314 |         struct kvec  *scratchiov = &scratch;
        |                       ^~~~~~~~~~
  lnet/klnds/socklnd/socklnd_lib.c:310:37: note: previous definition of 'scratchiov' with type 'struct kvec *'
    310 |                        struct kvec *scratchiov)
        |                        ~~~~~~~~~~~~~^~~~~~~~~~
  lnet/klnds/socklnd/socklnd_lib.c:315:24: error: 'pages' redeclared as different kind of symbol
    315 |         struct page  **pages      = NULL;
        |                        ^~~~~
  lnet/klnds/socklnd/socklnd_lib.c:309:63: note: previous definition of 'pages' with type 'struct page **'
    309 | ksocknal_lib_recv_kiov(struct ksock_conn *conn, struct page **pages,
        |                                                 ~~~~~~~~~~~~~~^~~~~

Fixes: 89df5e712f ("LU-11415 socklnd: improve scheduling algorithm")
Change-Id: I047746e93ef1b4421f0bf7ff0c39848996698331
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58441
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Hongchao Zhang <hongchao@whamcloud.com>
Reviewed-by: Cyril Bordage <cbordage@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>