ARM: dts: msm: Correct node name used for WCNSS reservation for 8909

There was a mistake in node name used for making
WCNSS carveout for 512 MB devices. Because of
this multiple reservations were being made for
same WCNSS region. Correct the node name and use
over-ridden node &peripheral_mem to make reservations.

Change-Id: I5c375c8eab2c2684bcbacb472b6fe384d10fde66
Signed-off-by: Susheel Khiani <skhiani@codeaurora.org>