bif: qpnp-bsi: eliminate redundant RBL1 command during register read

When performing a BIF slave register read of a single register
there is no need to specify a burst read length of 1.  All reads
are assumed to be of length 1 unless specified otherwise.
Therefore, remove the redundant RBL1 BIF bus command.

Change-Id: I000637a4bec5f6d2c9b48fa848c63779745b662a
Signed-off-by: David Collins <collinsd@codeaurora.org>