spi_qsd: teardown BAM pipes before turning off clocks

Tearing down BAM pipe causes accessing of BAM registers
(indirectly by the BAM driver). Register access in turn
requires clocking to the internal bus. Lack of clocking
may result in to crash.

Change-Id: I22bcfdd714024d980f5d66206a65657f9605d3b5
Signed-off-by: Sana Venkat Raju <c_vsana@codeaurora.org>