bnxt_re: add MAY_USE_DEVLINK dependency

bnxt_en depends on MAY_USE_DEVLINK; this is used to force bnxt_en
to be =m when DEVLINK is =m.

Now, bnxt_re selects bnxt_en. Unless bnxt_re also explicitly calls
out dependency on MAY_USE_DEVLINK, Kconfig does not force bnxt_re
to be =m when DEVLINK is =m, causing the following error:

drivers/net/ethernet/broadcom/bnxt/bnxt_vfr.o: In function
`bnxt_dl_register':
bnxt_vfr.c:(.text+0x1440): undefined reference to `devlink_alloc'
bnxt_vfr.c:(.text+0x14c0): undefined reference to `devlink_register'
bnxt_vfr.c:(.text+0x14e0): undefined reference to `devlink_free'
drivers/net/ethernet/broadcom/bnxt/bnxt_vfr.o: In function
`bnxt_dl_unregister':
bnxt_vfr.c:(.text+0x1534): undefined reference to `devlink_unregister'
bnxt_vfr.c:(.text+0x153c): undefined reference to `devlink_free'

Fix this by adding MAY_USE_DEVLINK dependency in bnxt_re.

Fixes: 4ab0c6a8 ("bnxt_en: add support to enable VF-representors")
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sathya Perla <sathya.perla@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>