This fix modifies the order of system includes to meet the ARM TF coding
standard. There are some exceptions in order to retain header groupings,
minimise changes to imported headers, and where there are headers within
the #if and #ifndef statements.

Change-Id: I65085a142ba6a83792b26efb47df1329153f1624
Signed-off-by: Isla Mitchell <isla.mitchell@arm.com>

Both Cortex-A75 and Cortex-A55 CPUs use the ARM DynamIQ Shared Unit
(DSU). The power-down and power-up sequences are therefore mostly
managed in hardware, and required software operations are considerably
simpler.

Change-Id: I68b30e6e1ebe7c041d5e67f39c59f08575fc7ecc
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>