ACPI: turn off all debug output by default

When CONFIG_ACPI_DEBUG=y, the default acpi_dbg_layer and acpi_dbg_level
values built into the ACPI CA have some debug output enabled.  We'd
rather be quiet unless the user actually specified the acpi.debug_level
argument.

This enables distros to ship with CONFIG_ACPI_DEBUG=y without
inundating users with debug output.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/bus.c

@@ -688,6 +688,14 @@ void __init acpi_early_init(void)
 	if (acpi_disabled)
 		return;
 
+	/*
+	 * ACPI CA initializes acpi_dbg_level to non-zero, which means
+	 * we get debug output merely by turning on CONFIG_ACPI_DEBUG.
+	 * Turn it off so we don't get output unless the user specifies
+	 * acpi.debug_level.
+	 */
+	acpi_dbg_level = 0;
+
 	printk(KERN_INFO PREFIX "Core revision %08x\n", ACPI_CA_VERSION);
 
 	/* enable workarounds, unless strict ACPI spec. compliance */