staging/mt7621-dma: mtk-hsdma.c->hsdma-mt7621.c

Also use KBUILD_MODNAME for module name.

This driver is only used by RALINK MIPS MT7621 SoCs. Tested by building
against that target using OpenWrt with Linux 5.10.10.

Fixes the following error:
error: the following would cause module name conflict:
  drivers/dma/mediatek/mtk-hsdma.ko
  drivers/staging/mt7621-dma/mtk-hsdma.ko

Cc: stable@vger.kernel.org
Cc: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Link: https://lore.kernel.org/r/20210130034507.2115280-1-ilya.lipnitskiy@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-dma/Makefile

 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_MTK_HSDMA) += mtk-hsdma.o
+obj-$(CONFIG_MTK_HSDMA) += hsdma-mt7621.o
 
 ccflags-y += -I$(srctree)/drivers/dma

drivers/staging/mt7621-dma/mtk-hsdma.c → drivers/staging/mt7621-dma/hsdma-mt7621.c

@@ -749,7 +749,7 @@ static struct platform_driver mtk_hsdma_driver = {
 	.probe = mtk_hsdma_probe,
 	.remove = mtk_hsdma_remove,
 	.driver = {
-		.name = "hsdma-mt7621",
+		.name = KBUILD_MODNAME,
 		.of_match_table = mtk_hsdma_of_match,
 	},
 };