Fix @ -> <at> substitution

When applying the AT91CAP9 patches upstream, something transformed
the '@' character into the ' <at> ' sequence.

The patch below restores the original form in all the places where
it has been modified (the AT91CAP9 files, the AT91SAM9260 files which
were copied from AT91CAP9, and a couple of other files where the
' <at> ' sequence was present).

Signed-off-by: Stelian Pop <stelian@popies.net>
diff --git a/cpu/arm926ejs/at91sam9/timer.c b/cpu/arm926ejs/at91sam9/timer.c
index 4e79466..c79ec7e 100644
--- a/cpu/arm926ejs/at91sam9/timer.c
+++ b/cpu/arm926ejs/at91sam9/timer.c
@@ -1,6 +1,6 @@
 /*
  * (C) Copyright 2007-2008
- * Stelian Pop <stelian.pop <at> leadtechdesign.com>
+ * Stelian Pop <stelian.pop@leadtechdesign.com>
  * Lead Tech Design <www.leadtechdesign.com>
  *
  * See file CREDITS for list of people who contributed to this