MIPS: Use mips_gic_present() in place of gic_present

In preparation for removing the gic_present global variable, switch to
using the mips_gic_present() function instead. For the most part this is
a straightforward substitution. In cases which previously wrapped the
GIC case in an #ifdef CONFIG_MIPS_GIC that #ifdef has been removed,
since mips_gic_present() will return a compile-time constant false
allowing the affected code to be optimised out anyway.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17044/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/lantiq/irq.c

@@ -61,10 +61,6 @@
 /* we have a cascade of 8 irqs */
 #define MIPS_CPU_IRQ_CASCADE		8
 
-#ifdef CONFIG_MIPS_MT_SMP
-int gic_present;
-#endif
-
 static int exin_avail;
 static u32 ltq_eiu_irq[MAX_EIU];
 static void __iomem *ltq_icu_membase[MAX_IM];