build: install into bin instead of sbin

Installs into bin instead of sbin per guidelines.

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: If7f7cfbbfcecdac9c8b0bc67825e97318818cb1d
diff --git a/Makefile.am b/Makefile.am
index 5178b67..82e370f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -6,7 +6,7 @@
 	argument.hpp \
 	certificate.hpp
 
-sbin_PROGRAMS = \
+bin_PROGRAMS = \
 	phosphor-certificate-manager
 
 phosphor_certificate_manager_SOURCES = \