BaseTools/BinToPcd: Open output file as text file

BaseTools/BinToPcd: Open output file as text file

https://bugzilla.tianocore.org/show_bug.cgi?id=1069

Undo changes from following commit:

https://github.com/tianocore/edk2/commit/83964ebc5e74549d6efc7134af19150a0b2079aa

Change the open mode for the output file from 'wb' to 'w' so the
output file is written as a text file and not a binary file.

This resolves the issue where the text file was not writable from
Python 3.x and also removes b'' from output file when the string
was encoded as a bytearray.

Cc: YanYan Sun <yanyan.sun@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Tested-by:YanYan Sun <yanyan.sun@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>