Replace dead OMAP_MUX_ERRORS with OMAP_MUX_WARNINGS

OMAP_MUX_ERRORS doesn't exist in Kconfig, therefore replacing all
references for it with OMAP_MUX_WARNINGS in the source code.
Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap1/mux.c

@@ -440,7 +440,7 @@ int __init_or_module omap1_cfg_reg(const struct pin_config *cfg)
 	}
 #endif
 
-#ifdef CONFIG_OMAP_MUX_ERRORS
+#ifdef CONFIG_OMAP_MUX_WARNINGS
 	return warn ? -ETXTBSY : 0;
 #else
 	return 0;