Fix various typos, scattered over the code.

Spelling corrections for (among other things):

* environment
* override
* variable
* ftd (should be "fdt", for flattened device tree)
* embedded
* FTDI
* emulation
* controller
diff --git a/doc/SPI/README.ti_qspi_flash b/doc/SPI/README.ti_qspi_flash
index 9064739..5cc1fd0 100644
--- a/doc/SPI/README.ti_qspi_flash
+++ b/doc/SPI/README.ti_qspi_flash
@@ -31,7 +31,7 @@
 Memory mapped read mode
 -----------------------
 In this, SPI controller is configured using configuration port and then
-controler is switched to memory mapped port for data read.
+controller is switched to memory mapped port for data read.
 
 Driver
 ------