TBB: remove PolarSSL SHA1 functions from the binary ...

Commit ea4ec3aad5e1 ("TBB: use SHA256 to generate the certificate
signatures") updated the cert_create tool to generate the
signatures using SHA256 instead of SHA1. Therefore, SHA1 is no
longer required.

This patch removes the SHA1 option from the PolarSSL configuration
file. The source file sha1.c is no longer needed and has been
excluded from the build. The SHA1 functions are no longer included
in the binary, reducing the memory footprint of BL1 and BL2 by
approximately 6 KB.

Change-Id: I72ea2cff03c0964c3eaadce148ec2ad2c6dde2e3

TBB: add PolarSSL based authentication module ...

This patch implements an authentication module based on the
PolarSSL library (v1.3.9) to verify the Chain of Trust when
Trusted Boot is enabled.

PolarSSL sources must be fetched separately. The POLARSSL_DIR
build option may be used to indicate the path to the PolarSSL
main directory (this directory must contain the 'include' and
'library' subdirectories).

To be able to build PolarSSL sources as a part of the Trusted
Firmware build process, the DISABLE_PEDANTIC flag in polarssl.mk
will tell the build system to remove the -pedantic option from
the CFLAGS.

Inclusion of PolarSSL increases the memory requirements of the BL1
and BL2 images. The following are the changes made to the FVP and
Juno platforms to cater for this when TRUSTED_BOARD_BOOT is
defined:

Changes on FVP:

  - BL1 and BL2 stacks have been increased to 4 KB
  - BL1(rw) section has been increased to 32 KB.
  - BL2 memory region has been increased to 112 KB

Changes on Juno:

  - BL1 and BL2 stacks have been increased to 4 KB
  - BL1(rw) section has been increased to 32 KB.
  - Trusted ROM region in Flash has been increased to 128 KB.
  - BL2 memory region has been increased to 116 KB

Change-Id: Ie87d80d43408eb6239c4acd0ec5ab2120e4e9e80