net: qed: use correct strncpy() size

passing the strlen() of the source string as the destination
length is pointless, and gcc-8 now warns about it:

drivers/net/ethernet/qlogic/qed/qed_debug.c: In function 'qed_grc_dump':
include/linux/string.h:253: error: 'strncpy' specified bound depends on the length of the source argument [-Werror=stringop-overflow=]

This changes qed_grc_dump_big_ram() to instead uses the length of
the destination buffer, and use strscpy() to guarantee nul-termination.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -3649,10 +3649,8 @@ static u32 qed_grc_dump_big_ram(struct qed_hwfn *p_hwfn,
 		     BIT(big_ram->is_256b_bit_offset[dev_data->chip_id]) ? 256
 									 : 128;
 
-	strncpy(type_name, big_ram->instance_name,
-		strlen(big_ram->instance_name));
-	strncpy(mem_name, big_ram->instance_name,
-		strlen(big_ram->instance_name));
+	strscpy(type_name, big_ram->instance_name, sizeof(type_name));
+	strscpy(mem_name, big_ram->instance_name, sizeof(mem_name));
 
 	/* Dump memory header */
 	offset += qed_grc_dump_mem_hdr(p_hwfn,