correctly put eeprom EE_HANDS at addr 0x0a (decimal 10). default to rev2 project. do not default EE_HANDS for the serial keymap

if you compare split_util.h with the original project by ahtn, the
address we look for isLeftHand config went from addr 7 to addr 10
(decimal). The EEP files were not updated.

EE_HANDS should not be enabled by default since it's more confusing for
most users

keyboards/lets_split/Makefile

@@ -1,3 +1,5 @@
+SUBPROJECT_DEFAULT = rev2
+
 ifndef MAKEFILE_INCLUDED
 	include ../../Makefile
-endif
+endif

keyboards/lets_split/eeprom-lefthand.eep

@@ -1,2 +1,2 @@
-:080000000000000000000001F7
+:0B0000000000000000000000000001F4
 :00000001FF

keyboards/lets_split/eeprom-righthand.eep

@@ -1,2 +1,2 @@
-:080000000000000000000000F8
+:0B0000000000000000000000000000F5
 :00000001FF

keyboards/lets_split/keymaps/serial/config.h

@@ -18,7 +18,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #define USE_SERIAL
 
-#define EE_HANDS
+// #define EE_HANDS
 
 
 #ifdef SUBPROJECT_rev1
@@ -29,4 +29,4 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #endif
 #ifdef SUBPROJECT_rev2fliphalf
 	#include "../../rev2fliphalf/config.h"
-#endif
+#endif