Config.in.legacy: fix check-package warnings

Config.in.legacy: fix check-package warnings

Fixes the following warnings:

Config.in.legacy:153: help text: <tab><2 spaces><62 chars> (http://nightly.buildroot.org/#writing-rules-config-in)
Config.in.legacy:154: help text: <tab><2 spaces><62 chars> (http://nightly.buildroot.org/#writing-rules-config-in)
Config.in.legacy:155: help text: <tab><2 spaces><62 chars> (http://nightly.buildroot.org/#writing-rules-config-in)
Config.in.legacy:156: help text: <tab><2 spaces><62 chars> (http://nightly.buildroot.org/#writing-rules-config-in)

which were introduced in commit
55c642287819a062d52e7f290c76ada778772fba ("arch/csky: remove
BR2_CSKY_DSP option")

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>