package/freerdp: security bump to version 2.1.1

package/freerdp: security bump to version 2.1.1

>From ChangeLog:
- CVE: GHSL-2020-100 OOB Read in ntlm_read_ChallengeMessage
- CVE: GHSL-2020-101 OOB Read in security_fips_decrypt due to
  uninitialized value
- CVE: GHSL-2020-102 OOB Write in crypto_rsa_common
- Enforce synchronous legacy RDP encryption count (#6156)
- Fixed some leaks and crashes missed in 2.1.0
- Removed dynamic channel listener limits
- Lots of resource cleanup fixes (clang sanitizers)

https://github.com/FreeRDP/FreeRDP/blob/2.1.1/ChangeLog

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>