drivers/bmp180: implementation cleanup

[aabadie]

This PR makes a little bit of cleanup in the bmp180 sensor driver implementation.

Following #5589, I also made some tests and noticed that this line was not needed. As I only tried with a samr21-xpro board, it needs confirmation by someone else.

[aabadie]

@PeterKietzmann, I applied the timing change requested by @keestux in #5589. Tested here, it works.

[PeterKietzmann]

Thx. If @keestux confirms until tomorrow I will merge this PR as bugfix.

[keestux]

I'm a bit overloaded. I'll try to look at it asap

[keestux]

Yes, I confirm that it works.
I've tested my particular error case (ENABLE_DEBUG in auto_init.c and build with -O0). This works.
And the normal case (-Os, without ENABLE_DEBUG in auto_init.c) works too.

[PeterKietzmann]

Thanks @aabadie and thanks @keestux for testing. Lets go with this PR and close #5589 instead. All right?

[PeterKietzmann]

I got the order to ask our release manager @kYc0o whether it is ok to merge this PR as a bugfix or if the clean-up is too much during feature freeze. Sorry for not acting as I promised :/

[keestux]

@PeterKietzmann Yes, go ahead and close #5589

[miri64]

If you say it's a bug-fix I would add it to the current release.

[kYc0o]

Of course if it's a bug-fix it should be in. Can anyone ACK this?

[PeterKietzmann]

ACK and go