lib/vsprintf: Reinstate printing of legacy clock IDs

When using the legacy clock framework, clock pointers are no longer
printed as IDs, as the !CONFIG_COMMON_CLK case was accidentally
considered an error case.

Fix this by reverting to the old behavior, which allows to distinguish
clocks by ID, as the legacy clock framework does not store names with
clocks.

Fixes: 0b74d4d763 ("vsprintf: Consolidate handling of unknown pointer specifiers")
Link: http://lkml.kernel.org/r/20190701140009.23683-1-geert+renesas@glider.be
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Petr Mladek <pmladek@suse.com>

lib/vsprintf.c

@@ -1798,7 +1798,7 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
 #ifdef CONFIG_COMMON_CLK
 		return string(buf, end, __clk_get_name(clk), spec);
 #else
-		return error_string(buf, end, "(%pC?)", spec);
+		return ptr_to_id(buf, end, clk, spec);
 #endif
 	}
 }