arm-cci: Add CCI-500 PMU support

arm-cci: Add CCI-500 PMU support

CCI-500 provides 8 event counters which can count any of the
supported events independently. The PMU event id is a 9-bit
value made of two parts.
	bits [8:5] - Source port
			0x0-0x6 Slave Ports
			0x8-0xD Master Ports
			0xf     Global Events to CCI
			0x7,0xe Reserved
	bits [0:4] - Event code (specific to each type of port)

The generic CCI-500 controlling interface remains the same with CCI-400.
However there are some differences in the PMU event counters.
 - No cycle counter
 - Upto 8 counters(4 in CCI-400)
 - Each counter area is 64K(4K in CCI400)
 - The counter0 starts at offset 0x10000 from the base of CCI

Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>