net: qed: correct qed_hw_err_notify() prototype

Change the prototype of qed_hw_err_notify() with the following:
* constify "fmt" argument according to printk() declarations;
* anontate it with __cold attribute to move the function out of
  the line;
* annotate it with __printf() attribute;

This eliminates W=1+ warning:

drivers/net/ethernet/qlogic/qed/qed_hw.c: In function
‘qed_hw_err_notify’:
drivers/net/ethernet/qlogic/qed/qed_hw.c:851:3: warning: function
‘qed_hw_err_notify’ might be a candidate for ‘gnu_printf’ format
attribute [-Wsuggest-attribute=format]
 len = vsnprintf(buf, QED_HW_ERR_MAX_STR_SIZE, fmt, vl);
 ^~~

as well as saves some code size:

add/remove: 0/0 grow/shrink: 2/4 up/down: 40/-125 (-85)
Function                                     old     new   delta
qed_dmae_execute_command                    1680    1711     +31
qed_spq_post                                1104    1113      +9
qed_int_sp_dpc                              3554    3545      -9
qed_mcp_cmd_and_union                       1896    1876     -20
qed_hw_err_notify                            395     352     -43
qed_mcp_handle_events                       2630    2577     -53
Total: Before=368645, After=368560, chg -0.02%

__printf() will also be helpful with catching bad format strings
and arguments.
Signed-off-by: Alexander Lobakin <alobakin@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qed/qed_hw.c

@@ -812,9 +812,8 @@ int qed_dmae_host2host(struct qed_hwfn *p_hwfn,
 	return rc;
 }
 
-void qed_hw_err_notify(struct qed_hwfn *p_hwfn,
-		       struct qed_ptt *p_ptt,
-		       enum qed_hw_err_type err_type, char *fmt, ...)
+void qed_hw_err_notify(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt,
+		       enum qed_hw_err_type err_type, const char *fmt, ...)
 {
 	char buf[QED_HW_ERR_MAX_STR_SIZE];
 	va_list vl;

drivers/net/ethernet/qlogic/qed/qed_hw.h

@@ -301,7 +301,8 @@ int qed_dmae_sanity(struct qed_hwfn *p_hwfn,
  * @param fmt - debug data buffer to send to the MFW
  * @param ... - buffer format args
  */
-void qed_hw_err_notify(struct qed_hwfn *p_hwfn,
+void __printf(4, 5) __cold qed_hw_err_notify(struct qed_hwfn *p_hwfn,
 					     struct qed_ptt *p_ptt,
-		       enum qed_hw_err_type err_type, char *fmt, ...);
+					     enum qed_hw_err_type err_type,
+					     const char *fmt, ...);
 #endif