accel/rocket: Fix indentation of Kconfig entry

The general indentation for the Kconfig lines is one tab, so adapt the
lines accordingly.

The description is correctly indented (1 tab + 2 spaces) so doesn't need
changes.

Fixes: ed98261b ("accel/rocket: Add a new driver for Rockchip's NPU")
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Tomeu Vizoso <tomeu@tomeuvizoso.net>
Link: https://lore.kernel.org/r/20250814113519.1551855-2-heiko@sntech.de