logcat: Fix --last usage option typo

Test: mm
Change-Id: I0b7a1615857acd4cd467f1ff1752eeae86d84eca
diff --git a/logcat/logcat.cpp b/logcat/logcat.cpp
index 94b8691..c204a16 100644
--- a/logcat/logcat.cpp
+++ b/logcat/logcat.cpp
@@ -321,7 +321,7 @@
                     "  -g, --buffer-size                      Get the size of the ring buffer.\n"
                     "  -G <size>, --buffer-size=<size>\n"
                     "                  Set size of log ring buffer, may suffix with K or M.\n"
-                    "  -L, -last       Dump logs from prior to last reboot\n"
+                    "  -L, --last      Dump logs from prior to last reboot\n"
                     // Leave security (Device Owner only installations) and
                     // kernel (userdebug and eng) buffers undocumented.
                     "  -b <buffer>, --buffer=<buffer>         Request alternate ring buffer, 'main',\n"