st_smi: Enhance the error handling

This commit does the following:
 - Reports error if SNOR flash is not found on the board
 - Changes smi_read_sr to return error using which a retry mechanism is
   implemented for reading flash status

Signed-off-by: Vipin Kumar <vipin.kumar@st.com>
Signed-off-by: Amit Virdi <amit.virdi@st.com>
Signed-off-by: Stefan Roese <sr@denx.de>
1 file changed