show_submenu: fix sed expression

The matching parentheses and | in sed expresssions need to be escaped
or sed will consider like normal characters.

Without this fix, make show_submenu was showing lines like this one:

  pro.menu.cpu.8MHzatmega328    ATmega328 (3.3V, 8 MHz)

It now properly outputs lines like this:

  pro        8MHzatmega328   ATmega328 (3.3V, 8 MHz)

This output is much less misleading to users especially newcomers.

0 files changed, 0 insertions, 0 deletions