docs: perf: Fujitsu: Fix htmldocs build warnings and errors

Running "make htmldocs" generates the following build errors and
warnings for fujitsu_uncore_pmu.rst:

Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst:20: ERROR: Unexpected indentation.
Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst:23: WARNING: Block quote ends without a blank line; unexpected unindent.
Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst:28: ERROR: Unexpected indentation.
Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst:29: WARNING: Block quote ends without a blank line; unexpected unindent.
Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst:81: ERROR: Unexpected indentation.
Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst:82: WARNING: Block quote ends without a blank line; unexpected unindent.

Add blank line before bullet lists, block quotes to fix build
errors, resolve warnings and properly render perf commands as
code blocks.

Signed-off-by: Gopi Krishna Menon <krishnagopi487@gmail.com>
Reviewed-by: Koichi Okuno <fj2767dz@fujitsu.com>
Fixes: bad11557 ("perf: Fujitsu: Add the Uncore PMU driver")
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Will Deacon <will@kernel.org>