n64: fix screen refresh rate regression [AJR]

Author: happppp

src/mame/nintendo/n64_m.cpp

@@ -1019,7 +1019,7 @@ void n64_periphs::vi_recalculate_resolution()
 
 	rectangle visarea = screen().visible_area();
 	// DACRATE is the quarter pixel clock and period will be for a field, not a frame
-	attotime period = attotime::from_ticks((vi_hsync & 0xfff) * (vi_vsync & 0xfff), DACRATE_NTSC / 2);
+	attotime period = attotime::from_ticks((vi_hsync & 0xfff) * (vi_vsync & 0xfff), DACRATE_NTSC * 2);
 
 	if (width <= 0 || height <= 0 || (vi_control & 3) == 0)
 	{
@@ -1043,7 +1043,7 @@ void n64_periphs::vi_recalculate_resolution()
 
 	visarea.max_x = width - 1;
 	visarea.max_y = height - 1;
-	screen().configure((vi_hsync & 0x00000fff)>>2, (vi_vsync & 0x00000fff), visarea, period);
+	screen().configure((vi_hsync & 0x00000fff) >> 2, (vi_vsync & 0x00000fff), visarea, period);
 }
 
 uint32_t n64_periphs::vi_reg_r(offs_t offset, uint32_t mem_mask)