samples: drivers: spi flash read and write in mem mapped on stm32h573

Define the Memory mapped mode on the stm32h573i_dk board
to read and write the external NOR octo-flash

Signed-off-by: Francois Ramu <francois.ramu@st.com>

Author: FRASTM

samples/drivers/spi_flash/boards/stm32h573i_dk.conf

@@ -1,2 +1,5 @@
-CONFIG_LOG=y
 CONFIG_STM32_MEMMAP=y
+
+CONFIG_LOG=y
+CONFIG_FLASH_LOG_LEVEL_INF=y
+