ARM: dts: msm: increase number of fastrpc sessions on SLPI for 8150

Increase the maximum number of concurrent fastrpc sessions that can
share the same SLPI context bank on 8150.

Change-Id: Ie0c135de497f9c94654d2d208585e5374a4a071d
Acked-by: Thyagarajan Venkatanarayanan <venkatan@qti.qualcomm.com>
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>