crosh-{dev,usb}: fix re-exec logic

The quoting was off on these tools leading to the error:
	./crosh-usb: 10: exec: ./crosh --usb: not found

BUG=None
TEST=`./crosh-dev` works (runs crosh in dev mode)
TEST=`./crosh-usb` works (runs crosh in usb mode)

Change-Id: I67fc809d96d45cefb89c1ed52722c689201bd761
Reviewed-on: https://chromium-review.googlesource.com/178936
Reviewed-by: Chris Masone <cmasone@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/crosh-dev b/crosh-dev
index afa3a23..f2e951d 100755
--- a/crosh-dev
+++ b/crosh-dev
@@ -6,7 +6,7 @@
 # dev-mode functionality for crosh
 
 if [ "$(basename $0)" = "crosh-dev" ]; then
-  exec "$(dirname $0)/crosh --dev"
+  exec "$(dirname $0)/crosh" --dev
 fi
 
 DEV_HELP='
diff --git a/crosh-usb b/crosh-usb
index b17e440..317874d 100755
--- a/crosh-usb
+++ b/crosh-usb
@@ -7,7 +7,7 @@
 # media.
 
 if [ "$(basename $0)" = "crosh-usb" ]; then
-  exec "$(dirname $0)/crosh --usb"
+  exec "$(dirname $0)/crosh" --usb
 fi
 
 USB_HELP='