selftests/powerpc/pmu: Fix sample field check in the mmcra_thresh_marked_sample_test

The testcase verifies the setting of different fields in Monitor Mode
Control Register A (MMCRA). In the current code, EV_CODE_EXTRACT macro
is used to extract the "sample" field, which then needs to be further
processed to fetch rand_samp_elig and rand_samp_mode bits. But the
current code is not passing valid sample field to EV_CODE_EXTRACT
macro. Patch addresses this by fixing the input for EV_CODE_EXTRACT.

Fixes: 29cf373c5766 ("selftests/powerpc/pmu: Add interface test for mmcra register fields")
Reported-by: David Binderman <dcb314@hotmail.com>
Link: https://lore.kernel.org/r/DB6P189MB0568CF002762C6C43AF6DF169CA89@DB6P189MB0568.EURP189.PROD.OUTLOOK.COM
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230301170918.69176-1-kjain@linux.ibm.com

selftests/powerpc/pmu: Add interface test for mmcra register fields

The testcase uses event code 0x35340401e0 to verify the settings for
different fields in Monitor Mode Control Register A (MMCRA). The fields
include thresh_start, thresh_stop thresh_select, sdar mode, sample and
marked bit. Checks if these fields are translated correctly via perf
interface to MMCRA.

Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
[mpe: Add error checking, drop GET_MMCR_FIELD, add to .gitignore]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220127072012.662451-21-kjain@linux.ibm.com