bl1: fix switch statements to comply with MISRA rules
bl1: fix switch statements to comply with MISRA rules

Ensure (where possible) that switch statements in bl1 comply with MISRA
rules 16.1 - 16.7

Return statements inside switch clauses mean that we do not comply with
rule 16.3.

Change-Id: I8342389ba525dfc68b88e67dbb3690a529abfeb1
Signed-off-by: Jonathan Wright <196f1acfb74bcda89687df012f9cb8daaef40244@arm.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware