defconfig: MSM8974: Add support for MSMSAMARIUM

Since MSMSAMARIUM supports single binary image with MSM8974,
add the MSMSAMARIUM config option in the same defconfig file.

Change-Id: I27d4cd9b1c74ccafd4c7fee5360b8518eed14670
Signed-off-by: Jay Chokshi <jchokshi@codeaurora.org>