Revert "add s390x arch build info at the netlink_deprecated_linux bridge driver"

This reverts commit b042dbe3128333b2e0f1d1459f9a1c77a34c4f7c.

The original commit breaks s390x, for example Docker build fails:

 * https://github.com/docker/docker/issues/26440

As discussed in the above issue:

  Even though char is unsigned by default on s390x, (gcc)go forces the type
  of RawSockaddr.Data to be signed.

  It makes no practical difference if these fields are signed or unsigned,
  it's just an API issue.

  The (assumed) reason for the original commit:

  For a while RawSockaddr.Data was unsigned during development of the gcc
  s390x port (not in an upstream release though). Probably the patch has
  been developed in this time frame.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>

libnetwork/drivers/bridge/netlink_deprecated_linux_notarm.go

@@ -1,4 +1,4 @@
-// +build !arm,!ppc64,!ppc64le,!s390x
+// +build !arm,!ppc64,!ppc64le
 
 package bridge
 

libnetwork/drivers/bridge/netlink_deprecated_linux_s390x.go

@@ -1,7 +0,0 @@
-// +build s390x
-
-package bridge
-
-func ifrDataByte(b byte) uint8 {
-	return uint8(b)
-}