cortex_a: Update instruction cache after setting a soft breakpoint

cortex_a: Update instruction cache after setting a soft breakpoint

Call armv7a_l1_d_cache_flush_virt() before writing the breakpoint,
to make sure the d-cache is clean and invalid at the breakpoint
location down to PoC.

Call armv7a_l1_d_cache_inval_virt() after writing the breakpoint
again, so that d-cache will pick up the modified code.
Call armv7a_l1_i_cache_inval_virt() after writing the breakpoint
to memory to make the change visible to the CPU.

Change-Id: I24fc27058d99cb00d7f6002ccb623cab66b0d234
Signed-off-by: Matthias Welwarsky <matthias@welwarsky.de>
Reviewed-on: http://openocd.zylin.com/3033
Reviewed-by: Paul Fertser <fercerpav@gmail.com>
Tested-by: jenkins