INIT UCode: reduce DSP initialization time

Push the mail at UCode boot time, not after the first update. This avoids a lot
of crazy busy-looping on the CPU side while waiting for the DSP to be
initialized.

Source/Core/Core/HW/DSPHLE/UCodes/INIT.cpp

@@ -10,6 +10,7 @@ INITUCode::INITUCode(DSPHLE *dsphle, u32 crc)
 	: UCodeInterface(dsphle, crc)
 {
 	DEBUG_LOG(DSPHLE, "INITUCode - initialized");
+	m_mail_handler.PushMail(0x80544348);
 }
 
 INITUCode::~INITUCode()
@@ -22,11 +23,6 @@ void INITUCode::Init()
 
 void INITUCode::Update()
 {
-	if (m_mail_handler.IsEmpty())
-	{
-		m_mail_handler.PushMail(0x80544348);
-		// HALT
-	}
 }
 
 u32 INITUCode::GetUpdateMs()