[PATCH] README: davinci: Clarify when SPL is used and the target devices.

[Adam Ford]

The documentation states that SPL is enabled in all config options
for the da850.  This incorrect, because devices booting from NOR
do not need the SPL to do the low level initializion because when
booting from NOR, the board is able to execute in place (XIP)

This also clarifies that SPL isn't only used for booting from SPI,
because it is also used for booting from MMC and NAND for those
devices supporting those boot options.

Signed-off-by: Adam Ford <aford173 at gmail.com>

diff --git a/doc/README.davinci b/doc/README.davinci
index 6522c24eea..607531af2a 100644
--- a/doc/README.davinci
+++ b/doc/README.davinci
@@ -37,11 +37,15 @@ Bootloaders
 ===============
 
 For DA850 an SPL (secondary program loader, see doc/README.SPL) is provided
-to load U-Boot directly from SPI flash. The SPL takes care of the low level
+to load U-Boot from SPI flash, MMC or NAND. The SPL takes care of the low level
 initialization.
 
-The SPL is built as u-boot.ais for all DA850 defconfigs. The resulting
-image file can be programmed to the SPI flash of the DA850 EVM/LCDK.
+The SPL is built as u-boot.ais for all DA850 defconfigs except those booting
+from NOR flash. The resulting image file can be programmed to the SPI flash
+of the DA850 EVM/LCDK.
+
+Devices that support booting from NOR utilize execute in place (XIP) and do
+not require SPL to perform low level initialization.
 
 Environment Variables
 =====================
-- 
2.25.1