msi-wmi: Use enums for scancodes

Use enums for consecutive scancodes, rename key names from MSI_WMI_* to
MSI_KEY_* and use tabs for whitespace in msi_wmi_keymap.

Signed-off-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>