perf/imx_ddr: Move ida_alloc() from ddr_perf_init() to ddr_perf_probe()

perf/imx_ddr: Move ida_alloc() from ddr_perf_init() to ddr_perf_probe()

Move ida_alloc() from helper ddr_perf_init() into ddr_perf_probe() to
clarify why ida_free() must be called at the error path.

Add return value check for ida_alloc().

Rename label 'cpuhp_state_err' to 'idr_free' to make the code clearer,
since two error paths now jump to this label.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Will Deacon <will@kernel.org>