BaseTools: Update Rsa2048Sha256Sign to use openssl standard options

BaseTools: Update Rsa2048Sha256Sign to use openssl standard options

sha256 is not the standard option. It should be replaced by sha -sha256.
Otherwise, it doesn't work in MAC OS.

In V2, update the option to sha1 -sha256.
In late openssl version >= 1.1, there is no sha option, but has sha1,sha256.
In previous openssl version < 1.1, there is no sha256, but has sha,sha1.
To work with all openssl version, use sha1 -sha256 for it.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liao Jui-peng <jui-pengx.liao@intel.com>
Signed-off-by: Liming Gao <liming.gao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>