make: fixed indention in (drivers/)Makefile.dep

[haukepetersen]

This is getting an annoying, repetitive task, once again fixing the indention in our dep Makefiles.

[aabadie]

I'm fine with the changes here but the include Makefiles (in drivers) need to be addressed as well if we agree on 2 spaces indendations for Makefile.

[miri64]

ACK, don't know how to fix the annoyance part though. Script is not possible, because something like the following is still possible and can not be written with spaces:

my-target: my-deps
ifeq (1,$(MYVAR))
	cmd1 # this line has to start with a tab
endif
	cmd2

[miri64]

if we agree on 2 spaces indendations for Makefile.

This is a convention for years now.

[miri64]

(but only for var definition ifs. It is not possible to start a target definition without a tab)