Fixed bug getting name to the calibration in mitiff writer

[TAlonglong]

Fixed bug getting name from the prerequisites when the prereq consist of DataQuery objects

• Tests added
• Passes flake8 satpy

[coveralls]

Coverage decreased (-0.008%) to 90.518% when pulling 947c6d3 on TAlonglong:bug-mitiff-writer-name-paramater into 1612d84 on pytroll:master.

[coveralls]

Coverage increased (+0.007%) to 90.533% when pulling 947c6d3 on TAlonglong:bug-mitiff-writer-name-paramater into 1612d84 on pytroll:master.

[codecov]

Codecov Report

Merging #1382 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1382   +/-   ##
=======================================
  Coverage   90.52%   90.53%           
=======================================
  Files         228      228           
  Lines       33377    33401   +24     
=======================================
+ Hits        30215    30239   +24     
  Misses       3162     3162           

Impacted Files	Coverage Δ
satpy/tests/writer_tests/test_mitiff.py	99.16% <100.00%> (+0.05%)	⬆️
satpy/writers/mitiff.py	91.88% <100.00%> (ø)

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[mraspaud]

LGTM, nice with the real testing.