ion: modify/add trace points

Add more info to ION trace points to help debug ION usage
related issues and optimizations.

Sample Output:

ion_alloc_buffer_start: client_name=708 heap_name=system len=4096
mask=0x2000000 flags=0x3 client_pid=708 current_comm=HwBinder:708_1
current_pid=881 buffer=0000000000000000

ion_alloc_buffer_end: client_name=708 heap_name=system len=4096
mask=0x2000000 flags=0x3 client_pid=708 current_comm=HwBinder:708_1
current_pid=881 buffer=ffffffea335bb380

ion_free_buffer: client_name=708 client_pid=708 current_comm=
HwBinder:708_1 current_pid=881 buffer=ffffffea335bb380 size=4096

Change-Id: I65fe2278697d442bdaabd1c78f61181bc9c10f6a
Signed-off-by: Vishwanath Raju K <vishk@codeaurora.org>