vsprintf: remove redundant and unused %pCn format specifier

%pC and %pCn print the same string, and commit 900cca294425 ("lib/vsprintf:
add %pC{,n,r} format specifiers for clocks") introducing them does not
clarify any intended difference. It can be assumed %pC is a default for
%pCn as some other specifiers do, but not all are consistent with this
policy. Moreover there is now no other suffix other than 'n', which makes a
default not really useful.

All users in the kernel were using %pC except for one which has been
converted. So now remove %pCn and all the unnecessary extra code and
documentation.

Acked-by: Stephen Boyd <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Signed-off-by: Luca Ceresoli <[e-mail]>
Reviewed-by: Petr Mladek <[e-mail]>
Tested-by: Petr Mladek <[e-mail]>
Reviewed-by: Yanteng Si <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Daniel Lezcano <[e-mail]>

Documentation/core-api/printk-formats.rst

···
 ::
 
 	%pC	pll1
-	%pCn	pll1
 
-For printing struct clk structures. %pC and %pCn print the name of the clock
+For printing struct clk structures. %pC prints the name of the clock
 (Common Clock Framework) or a unique 32-bit ID (legacy clock framework).
 
 Passed by reference.

Documentation/translations/zh_CN/core-api/printk-formats.rst

···
 ::
 
 	%pC	pll1
-	%pCn	pll1
 
-用于打印clk结构。%pC 和 %pCn 打印时钟的名称（通用时钟框架）或唯一的32位
+用于打印clk结构。%pC 打印时钟的名称（通用时钟框架）或唯一的32位
 ID（传统时钟框架）。
 
 通过引用传递。

lib/vsprintf.c

···
 	if (check_pointer(&buf, end, clk, spec))
 		return buf;
 
-	switch (fmt[1]) {
-	case 'n':
-	default:
 #ifdef CONFIG_COMMON_CLK
-		return string(buf, end, __clk_get_name(clk), spec);
+	return string(buf, end, __clk_get_name(clk), spec);
 #else
-		return ptr_to_id(buf, end, clk, spec);
+	return ptr_to_id(buf, end, clk, spec);
 #endif
-	}
 }
 
 static
···
  *      T    time64_t
  * - 'C' For a clock, it prints the name (Common Clock Framework) or address
  *       (legacy clock framework) of the clock
- * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address
- *        (legacy clock framework) of the clock
  * - 'G' For flags to be printed as a collection of symbolic strings that would
  *       construct the specific value. Supported flags given by option:
  *       p page flags (see struct page) given as pointer to unsigned long