net: ipa: add IPA v5.0 to ipa_version_string()

In the IPA device sysfs directory, the "version" file can be read to
find out what IPA version is implemented. The content of this file
is supplied by ipa_version_string(), which needs to be updated to
properly handle IPA v5.0.

Signed-off-by: Alex Elder <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ipa/ipa_sysfs.c

···
 		return "4.9";
 	case IPA_VERSION_4_11:
 		return "4.11";
+	case IPA_VERSION_5_0:
+		return "5.0";
 	default:
 		return "0.0";	/* Won't happen (checked at probe time) */
 	}