Replace err/dbg macros with pr_err/pr_debug

err macro has been removed entirely from the Linux kernel starting from
around v3.5, while the dbg macro has been deprecated. Since the lines
that were using err/dbg did not have access to the device, simply log as
a generic kernel log.
Use dev_err/dev_dbg when device is available

Previous commit used pr_err/pr_debug because it mistakenly assumed that
the device pointer was not available. This ensures that the driver uses
the dev_err and dev_dbg functions wherever it can.
Merge pull request #3 from nirenjan/deprecated-macros

Replace err/dbg macros with pr_err/pr_debug