[TASK] Add target specific macros for I/O and cache handling

Add target specific macros for
- IO read and write
- Data cache flush and invalidate
- Memory barrier

Change-Id: I447904c1ab246589e23133b27eebd8c59a18f192
[TASK] Add data cache handling for shared memory regions

Add data cache invalidate and flush to PDO triple buffer shared memory
and circular buffer. This change is needed to maintain cache coherency
between kernel and user layers.

Change-Id: I8ec84d9cff0992ee7e199c7d1bec560daee23f56
[TASK] Revise Xilinx Microblaze download elf script

Update download-elf scripts to download host and pcp application
for dual processor design (e.g. lx150t board).

Change-Id: I606e4423d43fc181f0d543cc1f2218e2f71948dc
Signed-off-by: Joerg Zelenka <joerg.zelenka@br-automation.com>
[TASK] Update sections for Xilinx Microblaze MN

Update functions to be placed in local memory for Xilinx Microblaze MN.

Change-Id: Idcc92f841087e9f5af0f763f163ac45d32bd4d4d
Signed-off-by: Joerg Zelenka <joerg.zelenka@br-automation.com>