Input: synaptics-rmi4 - replace deprecated strncpy

`strncpy` is deprecated for use on NUL-terminated destination strings [1]

Let's use memcpy() as the bounds have already been checked and this
decays into a simple byte copy from one buffer to another removing any
ambiguity that strncpy has.

Signed-off-by: Justin Stitt <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/rmi4/rmi_f34.c

···
 	if (buf[count - 1] == '\0' || buf[count - 1] == '\n')
 		copy_count -= 1;
 
-	strncpy(fw_name, buf, copy_count);
+	memcpy(fw_name, buf, copy_count);
 	fw_name[copy_count] = '\0';
 
 	ret = request_firmware(&fw, fw_name, dev);