Peer Manager fail to save a bonding data in SDK11 and SDK12

[Susheel Nuguru]

Noticed this for gcc with -0s optimization an application fail to save a bonding data. It is caused by byte alignment of

 static uint8_t buffer_memory[(n_blocks) * (block_size)]; 

in the macro PM_BUFFER_INIT in (pm_buffer.h).

[Susheel Nuguru]

Need to force it to 4-bytes word alignment like below in macro PM_BUFFER_INIT->pm_buffer.h

 __ALIGN(sizeof(uint32_t)) static uint8_t buffer_memory[(n_blocks) * (block_size)];