ARM: dts: msm: Increase rmtfs buffer size in 8937

The rmtfs buffer size requested by modem has been changed
1.5MB in 8937.
This results in a mismatch of requested buffer size
and allowable buffer size, thus causing an error and a
modem crash.

CRs-fixed: 1024120
Change-Id: Idef07dc305543379513ea9c62ea152b71ea7583f
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>