eth: fbnic: fix s390 build.

Building the fbnic nn s390, yield a build bug:

In function ‘fbnic_config_drop_mode_rcq’,
    inlined from ‘fbnic_enable’ at drivers/net/ethernet/meta/fbnic/fbnic_txrx.c:1836:4:
././include/linux/compiler_types.h:510:45: error: call to ‘__compiletime_assert_919’ declared with attribute error: FIELD_PREP: value too large for the field

The relevant mask is 9 bits wide, and the related value is the cacheline
aligned size of struct skb_shared_info.

On s390 the cacheline size is 256 bytes, and skb_shared_info minimum
size on 64 bits system is 320 bytes.

Avoid building the driver for such arch.

Reported-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/[email protected]/
Reported-by: Nathan Chancellor <[email protected]>
Fixes: 0cb4c0a ("eth: fbnic: Implement Rx queue alloc/start/stop/free")
Signed-off-by: Paolo Abeni <[email protected]>
Link: https://patch.msgid.link/5dfefd3e90e77828f38e68854b171a5b8b8c6ede.1721215379.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Paolo Abeni

drivers/net/ethernet/meta/Kconfig

@@ -20,6 +20,7 @@ if NET_VENDOR_META
 config FBNIC
 	tristate "Meta Platforms Host Network Interface"
 	depends on X86_64 || COMPILE_TEST
+	depends on S390=n
 	depends on PCI_MSI
 	select PHYLINK
 	help