MIPS: Malta: Implement get_c0_fdc_int()

Implement the weak get_c0_fdc_int() function for Malta. The Fast Debug
Channel (FDC) interrupt is obtained mainly depending on whether a GIC is
present. Vectored external interrupt mode isn't yet supported.

Signed-off-by: James Hogan <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/9143/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/mti-malta/malta-time.c

···
 	ts->tv_nsec = 0;
 }
 
+int get_c0_fdc_int(void)
+{
+	int mips_cpu_fdc_irq;
+
+	if (cpu_has_veic)
+		mips_cpu_fdc_irq = -1;
+	else if (gic_present)
+		mips_cpu_fdc_irq = gic_get_c0_fdc_int();
+	else if (cp0_fdc_irq >= 0)
+		mips_cpu_fdc_irq = MIPS_CPU_IRQ_BASE + cp0_fdc_irq;
+	else
+		mips_cpu_fdc_irq = -1;
+
+	return mips_cpu_fdc_irq;
+}
+
 int get_c0_perfcount_int(void)
 {
 	if (cpu_has_veic) {