tracing: Fix missing trace_boot_init_histograms kstrdup NULL checks

tracing: Fix missing trace_boot_init_histograms kstrdup NULL checks

[ Upstream commit 3c20bd3af535d64771b193bb4dd41ed662c464ce ]

trace_boot_init_histograms misses NULL pointer checks for kstrdup
failure.

Link: https://lkml.kernel.org/r/20211015195550.22742-1-mathieu.desnoyers@efficios.com
Fixes: 64dc7f6958ef5 ("tracing/boot: Show correct histogram error command")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>