target-arm: Fix typos in comments

Fix a variety of typos in comments in target-arm files.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@petalogix.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 191895c..d7f93d9 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -79,7 +79,7 @@
 typedef struct CPUARMState {
     /* Regs for current mode.  */
     uint32_t regs[16];
-    /* Frequently accessed CPSR bits are stored separately for efficiently.
+    /* Frequently accessed CPSR bits are stored separately for efficiency.
        This contains all the other bits.  Use cpsr_{read,write} to access
        the whole CPSR.  */
     uint32_t uncached_cpsr;