Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/arch/arm/mach-sa1100/cpu-sa1100.c b/arch/arm/mach-sa1100/cpu-sa1100.c
index 07d4e8b..aaa8acf 100644
--- a/arch/arm/mach-sa1100/cpu-sa1100.c
+++ b/arch/arm/mach-sa1100/cpu-sa1100.c
@@ -68,7 +68,7 @@
  * clock change in ROM and jump to that code from the kernel. The main
  * disadvantage is that the ROM has to be modified, which is not
  * possible on all SA-1100 platforms. Another disadvantage is that
- * jumping to ROM makes clock switching unecessary complicated.
+ * jumping to ROM makes clock switching unnecessary complicated.
  *
  * The idea behind this driver is that the memory configuration can be
  * changed while running from DRAM (even with interrupts turned on!)