libgo: don't include <linux/fs.h> when building gen-sysinfo.go

Removing this doesn't change anything at least with glibc 2.33.
The include was added in https://go.dev/cl/6100049 but it's not
clear why.

Fixes PR go/106266

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/417294

gcc/go/gofrontend/MERGE

-d295a0a2c96c0f7c3abd94fea3aa4e2303bf2af2
+ff68b1a147eb60082fd60c198db0ef5477ade938
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/sysinfo.c

@@ -158,9 +158,6 @@
 #if defined(HAVE_LINUX_ETHER_H)
 #include <linux/ether.h>
 #endif
-#if defined(HAVE_LINUX_FS_H)
-#include <linux/fs.h>
-#endif
 #if defined(HAVE_LINUX_REBOOT_H)
 #include <linux/reboot.h>
 #endif