tifm_7xx1: Merge media insert and media remove functions

Hardware does not say whether card was inserted or removed when reporting
socket events. Moreover, during suspend, media can be removed or switched
to some other card type without notification. Therefore, for each socket
in the change set the following is performed:
1. If there's active device in the socket it's unregistered
2. Media detection is performed
3. If detection recognizes supportable media, new device is registered

This patch also alters some macros and variable names to enhance clarity.

Signed-off-by: Alex Dubov <oakad@yahoo.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>