tools headers UAPI: Sync the linux/in.h with the kernel sources

Picking the changes from:

  70d0bb45 ("net: Correct spelling in headers")

Just a comment fix, addressing this perf build warning:

  Warning: Kernel ABI header differences:
    diff -u tools/include/uapi/linux/in.h include/uapi/linux/in.h

Please see tools/include/uapi/README for details.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/lkml/ZvrNlLdtXAZ1sIIj@x1Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/uapi/linux/in.h

@@ -141,7 +141,7 @@ struct in_addr {
  */
 #define IP_PMTUDISC_INTERFACE		4
 /* weaker version of IP_PMTUDISC_INTERFACE, which allows packets to get
- * fragmented if they exeed the interface mtu
+ * fragmented if they exceed the interface mtu
  */
 #define IP_PMTUDISC_OMIT		5