sample: driver: spi_flash: Add emsdp support

Add emsdp support in spi_flash driver sample
output log:
JEDEC QSPI-NOR SPI flash testing
==========================

Test 1: Flash erase
Flash erase succeeded!

Test 2: Flash write
Attempting to write 4 bytes
Data read matches data written. Good!

Signed-off-by: Siyuan Cheng <[email protected]>

Author: Siyuan Cheng

samples/drivers/spi_flash/boards/emsdp.conf

@@ -0,0 +1,7 @@
+#
+# Copyright (c) 2023 Synopsys.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+CONFIG_SPI_NOR=y