code: Use std::span where appropriate (#6658)

* code: Use std::span when possible

* code: Prefix memcpy and memcmp with std::

src/core/hw/lcd.cpp

@@ -64,7 +64,7 @@ template void Write<u8>(u32 addr, const u8 data);
 
 /// Initialize hardware
 void Init() {
-    memset(&g_regs, 0, sizeof(g_regs));
+    std::memset(&g_regs, 0, sizeof(g_regs));
     LOG_DEBUG(HW_LCD, "initialized OK");
 }