OPP: Fix file sending error by calculating size of file properly.

Use case:
Send and receive vcard file through OBEX multiple times (above 30 times)

Result:
Sometimes DUT is unable to begin the vcard sharing and a message is displayed
saying "File unknown file could not be sent".

Root cause:
In Some race conditions InputStream.available() returns zero which causing error.
According to java documentation InputStream.available() method provides a weak
guarantee so it isn't guaranteed to return the total number of bytes in the stream.

Fix:
Read the InputStream by read() API to calculate the actual length of data.

Change-Id: I3448d6d3c410ae9dc8213c1c1d5f23dba4a56982