ARM: 5863/1: fix bugs of clock source of NUC900

This patch fix following bugs:

1. typo error, CLOCK_EVT_MODE_PERIODIC -> CLOCK_EVT_FEAT_PERIODIC
2. TCSR register of timer1 missed PRESCALE
3. timer1 should be enabled before register it to clock source.

Signed-off-by: lijie <eltshanli@gmail.com>
Acked-by: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>