Add check for unmounted SD card in emmc (#26)

* Add check for unmounted SD card

* Implement it the better way and remove message Meme doesn't like

* Remove comma and remove dump option if no sd is inserted

Hopefully the last commit to this PR. Hopefully.

source/tegraexplorer/common/structs.c

@@ -99,4 +99,4 @@ menu_entry fwDump_typeMenu[] = {
 	{"Firmware format type:", COLOR_WHITE, {ISMENU | ISSKIP}},
 	{"Daybreak (prod.keys required!)", COLOR_BLUE, {ISMENU}},
 	{"ChoiNX", COLOR_VIOLET, {ISMENU}}
-};
+};