platform-drivers: msm: sps: enhance the debugging functions

The debugging functions in SPS driver are enhanced as follows:
1> Change some logging output from pr_info() to pr_debug() to reduce
   log amount.
2> Formalize the log content since some logs did not have the keyword
   which shows they are from SPS driver. This modification can help
   people find the error or other information from SPS driver more
   conveniently.
3> SPS driver did not output error messages in some places where an
   error is captured. Add error message output for these places.
4> SPS driver is used by some peripherals (such as SDCC) which have
   high throughput. When DEBUG level logging is enabled, the log
   output is tremendous and sometimes even hinders the analysis of
   the log, although some log messages are very helpful to the
   debugging of particular issues. Thus, add fine-grained DEBUG level
   log output control via debugfs.
5> Add the options via debugfs which dump the content of selected BAM
   registers. This can help analyze the BAM-related issues without
   additional software tools.

Change-Id: Ie97dc5d3b2736ea840125dad978e81abb960b27a
Signed-off-by: Yan He <yanhe@codeaurora.org>