net: qrtr: combine nameservice into main module

Previously with CONFIG_QRTR=m a separate ns.ko would be built which
wasn't done on purpose and should be included in qrtr.ko.

Rename qrtr.c to af_qrtr.c so we can build a qrtr.ko with both af_qrtr.c
and ns.c.

Signed-off-by: Luca Weiss <[e-mail]>
Reviewed-by: Bjorn Andersson <[e-mail]>
Tested-By: Steev Klimaszewski <[e-mail]>
Reviewed-by: Manivannan Sadhasivam <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/qrtr/Makefile

···
 # SPDX-License-Identifier: GPL-2.0-only
-obj-$(CONFIG_QRTR) := qrtr.o ns.o
+obj-$(CONFIG_QRTR) += qrtr.o
+qrtr-y	:= af_qrtr.o ns.o
 
 obj-$(CONFIG_QRTR_SMD) += qrtr-smd.o
 qrtr-smd-y	:= smd.o