BaseTools/GenFfs: Enlarge the size of 'AlignmentBuffer'
BaseTools/GenFfs: Enlarge the size of 'AlignmentBuffer'

As a workaround for the static code checkers, enlarge the size of the
string buffer 'AlignmentBuffer' so that it can hold all the digits of an
unsigned 32-bit integer plus the size unit character (e.g. 'M' & 'K').

Cc: Yonghong Zhu <78d981fe33a016071af5222c56d5cf77f30fb0b2@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <f387b71200577e27ccf5abb090fda0ddd187ec6e@intel.com>
Reviewed-by: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>

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