thunderbolt: Fix typos and magic number

Fix typo in tb_cfg_print_error() message.  Fix bytecount in struct
tb_drom_entry_port comment.  Replace magic number in tb_switch_alloc().
Rename tb_sw_set_unpplugged() and TB_CAL_IECS to fix typos.

[bhelgaas: no functional change intended]
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Andreas Noever <andreas.noever@gmail.com>