syscalls: add back legacy __NR_nfsservctl macro

The conversion from the old unistd.h file to syscall.tbl dropped the
nfsservctl macro. This one was handled inconsistently across architectures
in the original introduction of the syscall.tbl format, and I went the
other way on this.

The syscall was already gone in linux-3.1 before the current users
of the generic table (other than openrisc) first appeared, so nobody
could actally use it, but putting the number back helps for consistency
since there are build scripts that check the presence of all these
macros.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=2301919
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

scripts/syscall.tbl

@@ -53,6 +53,7 @@
 39	common	umount2				sys_umount
 40	common	mount				sys_mount
 41	common	pivot_root			sys_pivot_root
+42	common	nfsservctl			sys_ni_syscall
 43	32	statfs64			sys_statfs64			compat_sys_statfs64
 43	64	statfs				sys_statfs
 44	32	fstatfs64			sys_fstatfs64			compat_sys_fstatfs64