net: Trivial MLX4_DEBUG dependency fix.

CONFIG_MLX4_DEBUG works out to a def_bool y for those that have 
CONFIG_EMBEDDED set.  Make it depend on MLX4_CORE.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/net/Kconfig

@@ -2500,6 +2500,7 @@ config MLX4_CORE
 
 config MLX4_DEBUG
 	bool "Verbose debugging output" if (MLX4_CORE && EMBEDDED)
+	depends on MLX4_CORE
 	default y
 	---help---
 	  This option causes debugging code to be compiled into the