Fixed bug with gameboy->lcd.clk being updated multiple times

I also realized that every error has been due to (probably) the same sequence of opcodes
0xf0 to load [0xff41] into register A
0xe6 to logical and register A with IMM8
0x20 jump if not zero
all opcodes are (probably) fine and the lcd code itself is also ok
the main problem is dealing with these helper variables like clk and later timer and div