net: ravb: Fix registered interrupt names

net: ravb: Fix registered interrupt names

As interrupts are now requested from ravb_probe(), before calling
register_netdev(), ndev->name still contains the template "eth%d",
leading to funny names in /proc/interrupts.  E.g. on R-Car E3:

	89:  0      0  GICv2  93 Level  eth%d:ch22:multi
	90:  0      3  GICv2  95 Level  eth%d:ch24:emac
	91:  0  23484  GICv2  71 Level  eth%d:ch0:rx_be
	92:  0      0  GICv2  72 Level  eth%d:ch1:rx_nc
	93:  0  13735  GICv2  89 Level  eth%d:ch18:tx_be
	94:  0      0  GICv2  90 Level  eth%d:ch19:tx_nc

Worse, on platforms with multiple RAVB instances (e.g. R-Car V4H), all
interrupts have similar names.

Fix this by using the device name instead, like is done in several other
drivers:

	89:  0      0  GICv2  93 Level  e6800000.ethernet:ch22:multi
	90:  0      1  GICv2  95 Level  e6800000.ethernet:ch24:emac
	91:  0  28578  GICv2  71 Level  e6800000.ethernet:ch0:rx_be
	92:  0      0  GICv2  72 Level  e6800000.ethernet:ch1:rx_nc
	93:  0  14044  GICv2  89 Level  e6800000.ethernet:ch18:tx_be
	94:  0      0  GICv2  90 Level  e6800000.ethernet:ch19:tx_nc

Rename the local variable dev_name, as it shadows the dev_name()
function, and pre-initialize it, to simplify the code.

Fixes: 32f012b8c01ca9fd ("net: ravb: Move getting/requesting IRQs in the probe() method")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> # on RZ/G3S
Link: https://lore.kernel.org/r/cde67b68adf115b3cf0b44c32334ae00b2fbb321.1713944647.git.geert+renesas@glider.be
Signed-off-by: Jakub Kicinski <kuba@kernel.org>