[POWERPC] 8xx: Remove unneeded and misspelled prototype m8xx_calibrate_decr

m8xx_calibrate_decr seems to be a misspelled prototype for
mpc8xx_calibrate_decr. As it's not needed anyways, just remove it.
Signed-off-by: Jochen Friedrich <jochen@scram.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/platforms/8xx/m8xx_setup.c

@@ -31,7 +31,6 @@
 struct mpc8xx_pcmcia_ops m8xx_pcmcia_ops;
 #endif
 
-void m8xx_calibrate_decr(void);
 extern int cpm_pic_init(void);
 extern int cpm_get_irq(void);