GS: Correct GSIMR/GSCSR reg init, regression from previous release

pcsx2/GS.cpp

@@ -84,6 +84,8 @@ static __fi void gsCSRwrite( const tGS_CSR& csr )
 		gifUnit.gsFINISH.gsFINISHFired = true;
 		// Privilage registers also reset.
 		memzero(g_RealGSMem);
+		GSIMR.reset();
+		CSRreg.Reset();
 		gsVideoMode = GS_VideoMode::Uninitialized;
 		UpdateVSyncRate();
 		GetMTGS().SendSimplePacket(GS_RINGTYPE_RESET, 0, 0, 0);

pcsx2/GS.h

@@ -153,7 +153,6 @@ union tGS_CSR
 
 	void Reset()
 	{
-		_u64 = 0;
 		FIFO = CSR_FIFO_EMPTY;
 		REV = 0x1B; // GS Revision
 		ID = 0x55; // GS ID

pcsx2/Gif_Unit.cpp

@@ -85,6 +85,7 @@ bool Gif_HandlerAD(u8* pMem)
 	{ // FINISH
 		GUNIT_WARN("GIF Handler - FINISH");
 		CSRreg.FINISH = true;
+		gifUnit.gsFINISH.gsFINISHFired = false;
 	}
 	else if (reg == GIF_A_D_REG_LABEL)
 	{ // LABEL