Cosmetic: Fix a number of typos, no functional changes.

Fix various misspellings of things like "environment", "kernel",
"default" and "volatile", and throw in a couple grammar fixes.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
diff --git a/arch/arm/cpu/arm926ejs/at91/eflash.c b/arch/arm/cpu/arm926ejs/at91/eflash.c
index 3e21cdb..3f39264 100644
--- a/arch/arm/cpu/arm926ejs/at91/eflash.c
+++ b/arch/arm/cpu/arm926ejs/at91/eflash.c
@@ -28,7 +28,7 @@
  * by u-Boot commands.
  *
  * Note: Redundant environment will not work in this flash since
- * it does use partial page writes. Make sure the environent spans
+ * it does use partial page writes. Make sure the environment spans
  * whole pages!
  */