odyssey2/voice: remove unused function

src/devices/bus/odyssey2/voice.cpp

@@ -12,6 +12,9 @@ Hardware notes:
 Cartridge pins A,B,E,1,10,11 are repurposed for the extra speech ROM. This means
 that (European) cartridges using extra I/O won't work on it.
 
+TODO:
+- bees sound at level complete "MORE MORE MORE CHK CHK CHK" should be more rapid
+
 ******************************************************************************/
 
 #include "emu.h"
@@ -33,7 +36,6 @@ o2_voice_device::o2_voice_device(const machine_config &mconfig, const char *tag,
 
 void o2_voice_device::device_start()
 {
-	save_item(NAME(m_lrq_state));
 	save_item(NAME(m_control));
 }
 
@@ -68,7 +70,6 @@ void o2_voice_device::device_add_mconfig(machine_config &config)
 	SPEAKER(config, "mono").front_center();
 
 	SP0256(config, m_speech, 3.12_MHz_XTAL);
-	m_speech->data_request_callback().set(FUNC(o2_voice_device::lrq_callback));
 	// The Voice uses a speaker with its own volume control so the relative volumes to use are subjective, these sound good
 	m_speech->add_route(ALL_OUTPUTS, "mono", 1.00);
 
@@ -89,11 +90,6 @@ const tiny_rom_entry *o2_voice_device::device_rom_region() const
 //  mapper specific handlers
 //-------------------------------------------------
 
-WRITE_LINE_MEMBER(o2_voice_device::lrq_callback)
-{
-	m_lrq_state = state;
-}
-
 READ_LINE_MEMBER(o2_voice_device::t0_read)
 {
 	return m_speech->lrq_r() ? 0 : 1;

src/devices/bus/odyssey2/voice.h

@@ -48,9 +48,6 @@ private:
 	required_device<sp0256_device> m_speech;
 	required_device<o2_cart_slot_device> m_subslot;
 
-	DECLARE_WRITE_LINE_MEMBER(lrq_callback);
-
-	int m_lrq_state = 0;
 	u8 m_control = 0;
 };