ARCv2: smp: [plat-*]: No need to explicitly call mcip_init_early_smp()

MCIP now registers it's own probe callback with smp_ops.init_early_smp()
which is called by ARC common code, so no need for platforms to do that.

This decouples the platforms and MCIP and helps confine MCIP details
to it's own file.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/mcip.h

@@ -86,7 +86,6 @@ static inline void __mcip_cmd_data(unsigned int cmd, unsigned int param,
 	__mcip_cmd(cmd, param);
 }
 
-extern void mcip_init_early_smp(void);
 extern void mcip_init_smp(unsigned int cpu);
 
 #endif