The HSDK reset driver is only useful when building for an ARC HSDK
platform.

While at it, drop the "default n", as that is the default.

Fixes: e0be864f ("ARC: reset: introduce HSDKv1 reset driver")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
[p.zabel@pengutronix.de: rebased, renamed RESET_HSDK_V1 to RESET_HSDK]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>