FVP: Add Delay Timer driver to BL1 and BL31

FVP: Add Delay Timer driver to BL1 and BL31

SMMUv3 driver functions which are called from BL1 and BL31
currently use counter-based poll method for testing status
bits. Adding Delay Timer driver to BL1 and BL31 is required
for timeout-based implementation using timer delay functions
for SMMU and other drivers.
This patch adds new function `fvp_timer_init()` which
initialises either System level generic or SP804 timer based on
FVP_USE_SP804_TIMER build flag.
In BL2U `bl2u_early_platform_setup()` function the call to
`arm_bl2u_early_platform_setup()` (which calls
`generic_delay_timer_init()` ignoring FVP_USE_SP804_TIMER flag),
is replaced with `arm_console_boot_init()` and `fvp_timer_init()`.

Change-Id: Ifd8dcebf4019e877b9bc5641551deef77a44c0d1
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>